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Introduction to Yealink Teams Client Local Survivability

Ribbon Communications and Yealink® support uninterrupted voice services if a connectivity loss occurs between an enterprise site hosting Yealink Teams voice-related clients and the Microsoft® Phone System hosted in the Microsoft Azure™ cloud.

Support for Teams Client Survivability

The benefits of voice service survivability between enterprise sites hosting Yealink Teams voice-related clients and Phone System hosted in the Azure cloud include the following:

  • Enabling continued employee communication and collaboration with each other and with customers (that is, support employee capabilities to place and receive intra-office and inter-office voice calls and access backup call routing) regardless of Phone System availability
  • Increasing the ease of adoption for Phone System services at enterprise locations where such services are not yet rolled out

This best practice describes the Teams client survivability services available using Ribbon and Yealink products. The best practice also provides instructions for configuring, activating, and validating the services. For details of the Yealink and Ribbon collaboration, refer to the integrated solution announcement and related links.

Applicable Products

The following Yealink Teams clients collaborate with the Ribbon Communications SBC Edge to support survivability:

  • Conference Phone CP960
  • Desk Phone T58A
  • Desk Phone T56A
  • Desk Phone T55A (available Q3 2019)

 Yealink Teams Clients

 

Figure : Yealink Teams Clients - Conference and Desk Phones

 

For details about devices that support Teams voice services, refer to the Yealink Teams client products page for the latest feature descriptions and specifications for available models. 

Required Yealink Teams Client Firmware Version

The firmware version required to support survivability in a Teams context is: 

  • T5X Desk Phone Series: 58.15.0.38 and above
  • CP960 Conference Phone: 73.15.0.38 and above

Yealink Teams Client Reference Material

For product documentation that details the configuration and operation of the Teams clients, visit support.yealink.com

Ribbon Communications SBC Edge

The following SBC Edge offerings support Yealink Teams Client Local Survivability:

  • SBC SWe Lite, in both enterprise on-premises and Microsoft Azure-based deployments
  • All SBC 1000 hardware permutations
  • All SBC 2000 hardware permutations

 

Required SBC Edge Firmware Version

The SBC Edge firmware versions required to support Teams client survivability are Release 8.0.1 for the SBC SWe Lite and Release 8.0.1 for the SBC 1000/SBC 2000. Using earlier firmware versions is not supported and may result in conflicts and unexpected behavior.

Contact an authorized Ribbon Communications sales representative or partner to obtain the appropriate firmware release.

Teams Client Survivability Operation

The survivability capabilities available to Teams clients vary based on the accessibility of Phone System and the deployment type (on-premises or Azure).

Network Operation when Phone System is Accessible

When the Phone System is accessible, the Yealink Teams and SBC Edge operate as designed for the integrated solution.

SBC Edge on Enterprise Premises

When the SBC Edge is deployed on-premises, operation with the Yealink Teams clients is as follows with the Phone System accessible:

  • Both the Yealink Teams clients and the SBC Edge have continued Phone System access for signaling and media control.
  • Yealink Teams clients use Phone System (the "Primary Call Server") to establish intra-office, inter-office, and calls into the PSTN.
  • SBC Edge acts as a Teams Direct Routing certified SBC in support of Teams client access to the PSTN or to third-party, non-Teams voice infrastructure.
  • As a supplement to the Teams Phone System call services, the Yealink Teams clients register with the SBC Edge (the "Secondary Call Server") via SIP signaling.


Figure : Normal Operation when Teams Phone System is Accessible (SBC on enterprise premises)

SBC SWe Lite in Azure

When the the SBC SWe Lite is deployed in Azure, operation with the Yealink Teams clients is as follows with Phone System accessible:

  • Both the Yealink Teams clients and the SBC SWe Lite access Phone System in Azure for signaling and media control.
  • The Yealink Teams clients use Phone System ("Primary Call Server") to establish intra-office, inter-office, and calls into the PSTN.
  • The SBC SWe Lite acts as a Teams Direct Routing certified SBC in support of Teams client access to the PSTN or third party non-Teams voice infrastructure.
  • As a supplement to Phone System call services, the Yealink Teams clients register with the SBC SWe Lite ("Secondary Call Server") via SIP signaling. 

Figure : Normal Operation when Teams Phone System is Accessible (SBC SWe Lite in Azure)

Network Operation when Phone System is Not Accessible

SBC Edge on Enterprise Premises

Operation of the Yealink Teams clients and the SBC Edge (deployed on-premises) when the Phone System is not available (e.g. WAN outage, etc.) is characterized by:

  • The Phone System in Azure is no longer accessible for signaling and media control to the Yealink Teams clients and the SBC Edge;
  • The Yealink Teams clients use the services of the SBC Edge ("Secondary Call Server") via SIP signaling to establish intra-office, inter-office, and public calls into the PSTN.

Figure : Operation when Teams Phone System is Not Accessible (SBC on enterprise premises)

SBC SWe Lite in Azure

Operation of the Yealink Teams clients and the SBC Edge (deployed in Azure) when the Phone System is not available is characterized by:

  • The Phone System in Azure is no longer accessible for signaling and media control to the Yealink Teams clients.
  • The Yealink Teams clients use the services of the SBC SWe Lite in Azure ("Secondary Call Server") via SIP signaling to establish intra-office, inter-office, and public calls into the PSTN.

Figure : Operation when Teams Phone System is Not Accessible (SBC on enterprise premises)

WAN Outage May Impact Connection Between SBC SWe Lite in Azure and On-Premises Yealink Teams Client Devices

Please note that a WAN outage has the potential to sever the connection not only between the on-premises Yealink Teams clients and Phone System, but also the connection between the on-premises Yealink Teams clients and the SBC SWe Lite found in Azure. Please consider the location of the SBC (on-premises vs. Azure-based) carefully to ensure business availability requirements are properly addressed.

Initiating Survivability Operation From Yealink Devices

Outgoing Calls

To place outgoing calls using the SBC Edge instead of using the Phone System ( for example, if Phone System is temporarily unavailable), the Teams client user must access the Survivability (SIP) display of the Yealink device UI using the SIP "Quick Ball" icon. From the survivability UI, the user can place calls that route to their intended destination via the SBC Edge. 

Figure : "Quick Ball"-enabled Survivability on Yealink Teams Devices

Manual Intervention Required to Activate Yealink Device Survivability UI and to Switch Back to the Teams Client UI

The Yealink client device does not present the user with an indication that Phone System is unavailable to process a call establishment request from the Teams Client UI. If the user observes a condition that suggests Phone System is unavailable (e.g. a timeout on a call attempt, etc.):

  • The user must tap the SIP Quick Ball icon to switch to the Survivability UI to place new calls through the SBC;
  • Similarly, the user must tap the Teams Quick Ball icon to switch back to the Teams Client UI once Phone System advertises its availability.

Incoming Calls

The Yealink device UI automatically presents the appropriate UI (whether the Teams Client or Survivability) depending upon the originator of the incoming call (Phone System in the former case, and the SBC Edge in the latter). The user simply needs to answer the incoming call to engage in the call. 

SBC Edge Survivability Operation

When call routing is configured appropriately post-deployment, the SBC Edge automatically offers survivability services with no additional intervention

  • When incoming calls (intended for a Teams client) from the PSTN or a non-Teams client arrives at the SBC, the SBC validates the availability of the Phone System (latter being of highest priority within the route list). If the Teams System is recognized as being unavailable, the SBC routes the call directly to the subtended registered Yealink Teams client via SIP, as opposed to Phone System. For such an action to occur, the intended call recipient (the Yealink Teams client) must be mapped by the SBC as having a resolvable SIP-based client address. This resolution is possible through the subsequent SBC provisioning instructions.
  • Incoming SIP-based calls that arrive from the subtended Yealink Teams client are routed by the SBC as a standard SIP-based registered endpoint. These calls will be routed either to another subtended Yealink client or into the PSTN provided such routes are active and available. If no route is found, the SBC routes the call to the appropriate configured treatment.

Enabling Yealink Teams Client Local Survivability

Yealink Teams Client Device Prerequisites

Yealink Teams client-supporting devices (phones, etc.) must fulfill the following prerequisites prior to undertaking further actions:

  1. Devices must be configured and supporting Phone System voice services. To confirm support, please place a call from the Teams client UI to another Teams client within the enterprise. If such a call successfully completes, the device is configured to successfully offer Phone System services.
  2. Devices must be configured with a firmware release that supports survivability for Teams deployments.
  3. As an option, Yealink devices may be configured to communicate with the SBC Edge using TLS (Transport Layer Security, used for SIP signaling encryption) and SRTP (Secure Real-time Transport Protocol, used for media encryption).

    Use of Signaling and Media Encryption Strongly Recommended for Azure-based SBC Deployments

    Ribbon Communications and Yealink strongly recommend the use of TLS and SRTP for secure encrypted communication between the Yealink devices and the SBC, especially when the latter is deployed in the Azure public cloud. When the SBC is deployed in Azure, the use of encryption safeguards the communication that transits the public Internet. Please refer to the following links to configure the Yealink devices and the SBC for secure communication:

    • For the Yealink devices, refer to the relevant administrator guide, and undertake the configuration as a prerequisite step (now). An example administrator guide with encryption configuration instructions (for the desk Phone T58A) is available at support.yealink.com.

    • For the Ribbon SBC Edge, configure TLS & SRTP encryption later, within the SIP Local Registrar step and the Signaling Group configuration step. Note the following:
      • The SBC Edge should possess an X.509 certificate that is acquired during the Teams Direct Routing prerequisite step, including the CA (Certificate Authority) chain of trust. Refer to Configure a Certificate for the SBC Direct Routing Interface for more information regarding the assignment of the certificate during Teams Direct Routing setup. 
      • The SBC Edge X.509 certificate, exchanged during the TLS handshake with the Yealink device, must be signed by a CA that the Yealink devices will trust for successful communication. 
        • The list of recognized CAs are found in the relevant Yealink device administrator guide posted at support.yealink.com;
        • If the certificate is signed by an unrecognized CA, you must load the relevant sections of the certificate's chain of trust from the SBC into the Yealink devices so that the certificate is subsequently trusted. Refer to Working with Certificates for certificate chains within the SBC.

Assuming the conditions are fulfilled, the Yealink devices are ready for Teams-related survivability configuration, and should be updated only after the SBC Edge prerequisites and configuration are complete.

Yealink Device Supplementary Information

  • Refer above for valid firmware releases and products.
  • Refer to the relevant Yealink product documentation for Phone System-related device configuration in support of Teams-related phone calling.

Microsoft Teams Phone System Supplementary Information

Refer to the following sources of information for basic Microsoft Phone System features and deployment:

Ribbon SBC Edge Prerequisites

In all cases, the SBC Edge product must be deployed with a supporting firmware image. Once such an image is in place, please also ensure the following conditions are met depending upon the location (enterprise premises or Azure) of the SBC in the network topology.

SBC Edge Deployed On-Premises

For SBC Edge devices deployed on-premises, confirm the following:

  1. Initial setup is complete.

    • SBC 1000 and SBC 2000 initial setup steps

    • SBC SWe Lite on-premise deployment initial steps

      SBC SWe Lite Deployed On-Premises Initial Setup Clarifications

      The SBC SWe Lite initial setup instructions include content related to feature licensing, trials, and easy configuration. Note the following:

      1. You can choose to undertake feature licensing under the initial setup instructions, please ensure the minimum licensing requirements listed in step 2 are addressed;

      2. You can choose to configure the SBC SWe Lite for Yealink Teams Client Local Survivability with a trial license and as such, temporarily disregard the instructions in step 2; however, there are considerations:

        • Note the number of registered Yealink devices and session capacity will be limited to the capabilities of the trial license;

        • Ribbon does not support the use of trial licenses for live traffic (production) deployments.
      3. Please do not undertake any Easy Configuration Wizard actions at this time; the easy configuration actions in a Teams-related deployment has additional considerations, as defined in step 3

  2. Licensing has been acquired and properly assigned.

    • The following SIP registration license(s) are required for registering Yealink devices:

    • The following SIP session licenses may be required if the SBC Edge connects the IP-based SIP signaling and RTP media to and from subtended Yealink clients to an IP-based client (for example, a SIP trunk or a SIP-based IP PBX) instead of a legacy TDM connection (for example, a PRI/BRI trunk or an analog FXS/FXO destination):
  3. Teams Direct Routing (DR) basic configuration has been undertaken. Teams DR basic configuration is documented in the on-premises best practice. Please ensure all instructions are executed as documented in the following sections of that best practice:
  4. Networking device updates have been applied to permit SBC Edge ↔ subtended registered Yealink client device communication. The SBC Edge and the Yealink clients that will attempt to register may not be in the same office/LAN; they may be located in different offices accessible through the enterprise's WAN, or may only be accessible through the internet. As such, the following devices must be configured to ensure successful communication between the parties:
    • Any intervening routers undertaking LAN ↔ WAN addressing conversions, such as those related to NAT;

    • Any intervening firewalls undertaking network traffic filtering actions.

      Contact Enterprise IT to Facilitate IP-based Communications

      Please contact your IT administrator to ensure communication can be undertaken between the network segments hosting the Yealink Teams client devices and the SBC Edge. The IT administrator should be knowledgeable regarding the private IP addresses assigned to all devices, along with the required routing to achieve inter-device communications.

Once the previous steps have been completed, the SBC Edge device is ready for further configuration for Yealink Teams Client Local Survivability.

SBC SWe Lite Deployed in Azure

For an SBC SWe Lite deployed in Azure, confirm the following:

  1. Initial setup is complete per the instructions applicable for an Azure deployment.

    SBC SWe Lite Deployed in Azure Initial Setup Clarifications

    The SBC SWe Lite initial setup instructions include content related to feature licensing, trials, and easy configuration. Note the following:

    1. You can choose to undertake feature licensing under the initial setup instructions, please ensure the minimum licensing requirements listed in step 2 are addressed.

    2. You can choose to configure the SBC SWe Lite for Yealink Teams Client Local Survivability with a trial license and as such, temporarily disregard the instructions in step 2; however, there are considerations:

      • Note the number of registered Yealink devices and session capacity will be limited to the capabilities of the trial license.

      • Ribbon does not support the use of trial licenses for live traffic (production) deployments.
    3. Please do not undertake any Easy Configuration Wizard actions at this time; the easy configuration actions in a Teams-related deployment has additional considerations, as defined below in step 3.
  2. Licensing has been acquired and properly assigned.

    • SIP registration license(s) (namely one or more instances of the SBC-SWELITE-LIC-RG-CLOUD) are absolutely required, to enable the registration of Yealink devices. 

    • SIP session licenses are required, as the IP-based SIP signaling and RTP media to/from the subtended Yealink clients is connected by the SBC SWe Lite to an IP-based client (e.g. a SIP trunk, a SIP-based IP PBX, etc.)

      SBC Edge License Acquisition

      For instructions on how to obtain and apply licenses, refer to Working with Licenses.

  3. Teams Direct Routing (DR) basic configuration has been undertaken. Teams Direct Routing basic configuration is documented in the Azure-related best practice. Please ensure all instructions are executed as documented in the following sections of that best practice:
  4. Networking device updates have been applied to permit Azure-based SBC Edge ↔ enterprise premises-based Yealink client device communication. The SBC Edge and the Yealink clients that will attempt to register will likely communicate across the Internet; as such, the following devices/constructs must be configured to ensure successful communication between the parties:

After you complete the steps above, the SBC SWe Lite in Azure is ready for further configuration for Yealink Teams Client Local Survivability.

Configuration Instructions

SBC Edge Configuration to Accept Yealink Devices Registration and Undertake Teams Client-Related Survivability Routing

Introduction

The following instructions detail how to configure the Ribbon SBC to accept Yealink Teams client devices registrations and to route calls properly between the devices and the PSTN. Please note the following context prior to the configuration being undertaken:

  1. Create a new SIP Local Registrar instance to which the Yealink devices register via SIP, including client registration authentication and potentially a new TLS Profile ID
  2. Create new call routing for use whenever a Yealink device needs to place calls via the SBC. 

    1. Create a new Call Routing Table instance.

    2. Create two new Transformation Table instances (one for intra-office calling and one for PSTN access), each with an entry to pass the user dialed digits through for routing purposes;

    3. Specify two new call routing entries to identify the final instructions for intra-office and PSTN routing for a Yealink device-originated call.

      Intra-Office and PSTN Routing Clarifications

  3. Create a new Signaling Group instance that will be associated with the new local registrar instance you just created;
  4. Update the pre-existing Call Routing Table instance (associated with the incoming PSTN trunk) to include updated routing for call processing that uses the newly created Signaling Group instance when Phone System is unavailable:

    1. Create a new Transformation Table instance and entries to modify the incoming dialed digits received from the PSTN for local routing to the newly created SIP local registrar instance.

    2. Specify a new call routing entry to identify the final instructions for routing to an SBC-subtended Yealink device.

      Pre-Existing Call Route Table Instance Clarifications

  5. Confirm the new Signaling Group instance associated with the new SIP Local Registrar instance is active.

Example SBC Network Diagram

To aid in the comprehension of the subsequent configuration instructions, please refer to the example network presenting pre-existing attribute values and device identifiers, along with soon to be added (identified in green italic font) attributes and values. Note select values (denoted with an X) are redacted for privacy purposes.

Figure : Sample Configuration Attribute Values for Example SBC Network Topology


SBC Configuration

  1. Access the WebUI, and click the Settings tab.
    1. In the left navigation page, access SIP > Local Registrars Table.

      1. Click () to add a row.

      2. In the Create SIP Local Registrar dialog box, type the desired identifier name and maximum number of registering clients for your new SIP local registrar instance. For our example deployment, the entered name is LocalReg.

        Registrar Provisioning Reference Information

      3. Click OK.

        Figure : Newly Created Example SIP Local Registrar Instance "LocalReg", to Which Yealink Devices Will Register as SIP Endpoints

    2. In the left navigation page, access SIP > Local/Pass-thru Auth Tables

      1. Click () to add a local pass-through authorization table.

      2. In the Description dialog box, type the desired Local Pass-through Authorization Table name. For our example deployment, the name specified is Local registration table.

      3. Click OK.

        Figure : Newly Created Example Local Pass-through Authorization Table instance "Local Registration table", that will shortly define acceptable credentials for successful registration

        Local Pass-through Authorization Tables Provisioning Reference Information

      4. In the left navigation page, access SIP > Local/Pass-thru Auth Tables, and select (click) the new Local Pass-through Authorization Table just created. In example deployment, the entered name is Local registration table. The table displays under the tabs, with the note:  -- Table is empty --

        1. Click the Create Local Pass-through Authorization Entry) icon

        2. Specify the following values for fields:

          Table : Local Pass-through Authorization Entry Attributes

          Field

          Required Entry

          Type of Address of Record

          Local, to signify the SBC is the registrant of record.

          Address of Record URI

          Specify the acceptable Address of Record (AOR) URI from a potential valid registering endpoint. In the example deployment, one such AOR URI is sip:30001.

          User Name

          Specify the acceptable user name from the registering endpoint. In the example deployment, one acceptable User Name is 30001 .

          Enter Password

          Specify the password the registering endpoint must submit for successful registration.

          Confirm Password

          Type the same password as entered above for confirmation.

          Local Pass-through Authorization Table Entries Provisioning Reference Information

        3. Click OK.

          Figure : Highlighted Example New Local Pass-through Authorization Entry

        4. Repeat steps 1, 2, and 3 for each remaining possible valid registering endpoints. In the example deployment, steps 2 and 3 are repeated for Yealink device 30003.

          Use of Local Pass-through Authorization Table is Strongly Recommended

          Ribbon and Yealink strongly recommend the use of the optional Local Passthrough Authorization Table, especially for Azure-based SBC deployments. The use of the Local Passthrough Authorization Table deters the fraudulent use of your enterprise's SIP trunking services by unauthorized users.

      5. Optional Step for encrypted SIP signaling: Create the TLS profile to define the cryptographic parameters for the SIP signaling between the subtended Yealink devices and the SBC.

        1. In the WebUI, click the Settings tab.
        2. In the left navigation pane, go to Security > TLS Profiles.

        3. Click the CreateTLS Profile ( ) icon at the top of the TLS Profile page.
        4. Configure the parameters shown below. Leave all other parameters as default.

          Table : New TLS Profile Entry Attributes for Registered Yealink SIP Clients ↔ SBC Communication

          Field

          Required Entry

          Description

          Specify a descriptive name for the entry. A sample name may be Yealink SIP Client SBC Signaling

          TLS Protocol

          Set the administrative state to TLS 1.0 - 1.2

          Mutual Authentication

          Specify the authentication as Disabled.

          Client Cipher List

          Select a cipher value (this value must be supported by the subtended registered Yealink clients). See above for guidelines. Ribbon recommends TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384. 

          Validate Server FQDN

          Specify the validation as Disabled.

          All other fieldsPlease leave all default values as-is for basic SIP signaling encryption purposes.

        5. Click OK, and confirm the presence of the new TLS Profile entry. 

          Use of Signaling and Media Encryption Strongly Recommended for Azure-based SBC Deployments

          While optional, Ribbon Communications and Yealink strongly recommend the use of TLS and SRTP for secure encrypted communication between the Yealink devices and the SBC, especially when the latter is deployed in the Azure public cloud. For more information, please refer above.

          TLS Profile Provisioning Reference Information

  2. Access the WebUI, click the Settings tab.

    1. In the left navigation pane, go to Call Routing > Call Routing Table. 

      1. Click ().

      2. Enter a descriptive name in the Description text field; for this deployment example, the value is From Local SIP EP

      3. Click OK.

        Figure : Highlighted Example New Call Routing Table for Registered SIP Client-Initiated Call Processing

        Call Routing Table Provisioning Reference Information

    2. In the WebUI, click the Settings tab.
      1. In the left navigation pane, go to Call Routing -> Transformation .

      2. Click the Create ( ) icon.

      3. In the Description dialog box, enter the desired Transformation Table name identifier for calling to the PSTN. For our example deployment, the entered name is from SIP to IMS.

      4. Click OK .

        Figure : Highlighted New Transformation Table for Registered SIP Clients to Call the PSTN

        Transformation Table Provisioning Reference Information

      5. In the left navigation page, go to Transformation, and select (click) the new Transformation Table just created. In example deployment, the entered name is  from SIP to IMS. The table displays under the tabs, with the note: -- Table is empty --

        1. Click the Create ( ) icon

        2. Type or select the following values to specify the passthrough of dialed digits from the subtended registered Yealink Survivability (SIP) client to the PSTN:

          Table : New Transformation Table Entry Attributes for Registered SIP Clients to Reach the PSTN

          Field

          Required Entry

          Description

          Specify a descriptive name for the entry. In the example deployment, the entered name is SIP to PSTN.

          Admin State

          Set the administrative state to Enabled.

          Type (Input Field)

          Specify the type for input as Called Address/Number.

          Value (Input Field)

          Specify an asterisk (.*) to indicate acceptance of any digits.

          Type (Output Field)

          Specify the type for output as Called Address/Number.

          Value (Output Field)

          Specify the value of output as \1 to indicate that digits received will be passed through to the outbound route without any change made.

          Transformation Table Entries and Digit Manipulation Provisioning Reference Information

        3. Click OK .

          Figure : Highlighted New Transformation Table Entry for Registered SIP Clients to Call the PSTN

    3. In the WebUI, click the Settings tab.
      1. In the left navigation pane, go to Call Routing > Transformation.

      2. Click the Create ( ) icon.

      3. In the Description dialog box, enter the desired Transformation Table name identifier for intra-office calling. For our example deployment, the entered name is from SIP to SIP.

      4. Click OK.

        Figure : Highlighted New Transformation Table for Registered SIP Clients to Call Other SIP Clients in the Office

        Transformation Table Provisioning Reference Information

      5. In the left navigation page, go to Transformation, and select (click) the new Transformation Table just created for intra-office calling. In example deployment, the entered name is  from SIP to SIP. The table will appear under the tabs, with a note stating – Table is empty --

        1. Click the Create ( ) icon

        2. Enter or select the following values into the pop-up window, to specify the pass through of dialed digits from the subtended registered Yealink Survivability (SIP) client to another subtended registered Yealink Survivability (SIP) client.

          Table : Transformation Table Entry Attributes for Intra-Office Calling

          Field

          Required Entry

          Description

          Please use a descriptive name for the entry. In the example deployment, the entered name is SIP to SIP.

          Admin State

          Enabled

          Type (Input Field)

          Called Address/Number

          Value (Input Field)

          Please enter a regular expression to confirm a private dial plan number that conforms to the private dial plan assigned to the registered SIP clients. In the example deployment, the entered expression is ^(3\d{4})$, signifying the called digits must be 5 characters in length, and must start with a 3.

          Type (Output Field)

          Called Address/Number

          Value (Output Field)

           \1 , signifying matching digits received will be passed through to the outbound route without change.

          Transformation Table Entries and Digit Manipulation Provisioning Reference Information

        3. Click OK .

          Figure : Highlighted New Transformation Table Entry for Registered SIP Clients to Call Other Registered SIP Clients

    4. In the WebUI, click the Settings tab.
      1. In the left navigation pane, go to Call Routing > Call Routing Table and select the newly created Call Routing Table; for our example deployment, the newly created table is From Local SIP EP. 

        1. Click the Create Routing Entry ( ) icon to create the route for calling into the PSTN.

          1. Enter the following values into the pop-up window:

            Table : Call Routing Entry Attributes for Calling from Registered Yealink Devices to the PSTN

            Field

            Required Entry

            DescriptionEnter an informative name in the text field; for our example deployment, the value is to IMS

            Admin State

            Select Enabled

            Number/Name Transformation Table

            Select the newly created Transformation Table instance to which calls from a subtended registered Yealink device will be routed to the PSTN. For the example deployment, the value is from SIP to IMS.

            Destination TypeSelect Normal
            Destination Signaling GroupsSelect the PSTN-related Signaling Group. For the example deployment, the value is IMS
            All other fieldsPlease leave all default values as-is for basic configuration purposes.

            Call Routing Table Entry Provisioning Reference Information

          2. Click OK .

            Figure : Example Call Routing Entry Attributes for Calling from Registered Yealink Devices to the PSTN

        2. Click the Create Routing Entry ( ) icon once again to create the route entry for intra-office calling.

          1. Type or choose the following values:

            Table : Call Routing Entry Attributes for Calling from Registered Yealink Devices to Other Registered Yealink Devices

            Field

            Required Entry

            DescriptionType a descriptive name in the text field; for the example deployment, the value is SIP TO SIP.

            Admin State

            Select Enabled

            Number/Name Transformation Table

            Select the newly created Transformation Table instance to which calls from a subtended registered Yealink device will be routed when attempting to reach another subtended registered Yealink device. For the example deployment, the value is from SIP to SIP.

            Destination TypeSelect Registrar Table
            Destination Signaling GroupsSelect the newly created SIP Local Registrar-related Signaling Group to which the subtended registered Yealink devices are associated. For the example deployment, the value is LocalReg
            All other fieldsLeave all other default values as-is for basic configuration purposes.

          2. Click OK.

            Figure : Example Call Routing Entry Attributes for Calling from Registered Yealink Devices to Other Registered Yealink Devices

             

      2. Review and confirm the two new Call Routing Table entries in the newly created Call Routing Table.

        Figure : New Priority Call Routing Table Entry


  3. Access the WebUI, click the Settings tab.

    1. In the left navigation pane, go to Signaling Groups.

    2. From the top menu bar, click Create Signaling Group and select SIP Signaling Group (note: for the SBC SWe Lite, select Add SIP SG )

    3. Create the SIP Signaling Group using the following configuration:

      Table : SIP Signaling Group Attribute Values for Registered Yealink Devices

      Field

      Required Entry

      DescriptionEnter an informative name in the Description text field; for the example deployment, the value is LocalReg .
      Admin StateSelect Enabled
      Call Routing TableSelect the recently created Call Routing Table Instance that will define routing for calls that originate from the subtended registered Yealink devices. For the example deployment, the value is from Local SIP EP .
      SIP Mode Select the Local Registrar value.
      Registrar Select the recently created SIP Local Registrar instance to which subtended Yealink devices will advertise their presence. For the example deployment, the value is LocalReg.
      Challenge RequestSelect Enable
      Local/Pass-thru Auth TableSelect the recently created Local Pass-through Authorization Table that defines the credentials the subtended Yealink devices must present to the SBC to be successfully recognized (registered). For the example deployment, the value is Local registration table.

      Media List ID (Optional Step for encrypted media)

      If you specified a new TLS Profile ID, please select the Media List ID value associated with Phone System Signaling Group for SRTP communication with the registered subtended Yealink client devices. The value to be selected should be MS Teams Media List , originally created through the use of the Teams DR-related easy configuration wizard during the SBC setup. The contains SRTP cryptographic settings that can be used for SBC Edge ↔ subtended registered Yealink client device encrypted media exchange.

      NOTE: For details on Media List ID configuration including the setup of attributes related to media encryption, please refer to Managing Media Lists and Managing SDES-SRTP Profiles .

      Listen Port

      Click the ( ) icon to create a new instance of the SIP Listen Port, and update as follows:

      Option 1: For unencrypted SBC Edge ↔ subtended registered Yealink client device communication, please enter the Port value as 5060, the Protocol value as UDP, and the TLS Profile ID as N/A.

      Option 2: For encrypted SBC Edge ↔ subtended registered Yealink client device communication (you must have specified a new TLS Profile ID entry earlier), please enter the Port value as 5061, the Protocol value as TLS, and the TLS Profile ID as the new entry created earlier (e.g. Yealink SIP Client SBC Signaling) .

      Federated IP/FQDN

      Click the ( ) icon to create a new instance of the Federated IP/FQDN, and specify as follows to identify the networking IP addresses of your Yealink Teams client devices, supplied by the enterprise IT administrator. For our example deployment, the IP/FQDN is entered as XXX.0.0.0, with the Netmask/Prefix as 255.0.0.0, meaning the signaling group will accept communication with any host (i.e. Yealink device) that presents a host IP of anywhere from XXX.0.0.1 → XXX.255.255.254

      All other fieldsPlease leave all default values as-is for basic configuration purposes.

      Signaling Group Provisioning Reference Information

      For details on Signaling Group configuration attributes described above including modification of fields with default values, refer to Creating and Modifying SIP Signaling Groups.

    4. Click OK . The  new SIP Signaling Group (in the example deployment, named LocalReg ) may be expanded to present the following sample attributes.

      Figure : Example SIP Signaling Group Configuration for Connection to Registered Yealink Teams Devices; Key User-Supplied values Highlighted

  4. In the WebUI, click the Settings tab.

    1. In the left navigation pane, Call Routing -> Transformation .

      1. Click the Create ( ) icon.

      2. In the Description dialog box, enter the desired Transformation Table name identifier for calls received from the PSTN and destined for a subtended Yealink device. For our example deployment, the entered name is from IMS to SIP.

      3. Click OK .

        Figure : Highlighted New Transformation Table for PSTN Call Routing to Registered Yealink Devices

        Transformation Table Provisioning Reference Information

      4. In the left navigation page, go to Transformation, and select (click) the new Transformation Table just created. In example deployment, the entered name is  from IMS to SIP. The table will appear under the tabs, with a note stating – Table is empty --

        1. Click the Create ( ) icon

        2. Enter or select the following values into the pop-up window, to specify the modification of dialed digits from the PSTN to reach a subtended registered Yealink Survivability (SIP) client:

          Table : New Transformation Table Entry Attributes for a PSTN Call to Reach a Specific Registered Yealink Device

          Field

          Required Entry

          Description

          Please use a descriptive name for the entry. In the example deployment, the entered name is Entry ID 1

          Admin State

          Enabled

          Type (Input Field)

          Called Address/Number

          Value (Input Field)

          Please enter a regular expression to define the Teams Phone Number assigned to the Yealink device with the survivability. In the example deployment, the entered expression is \+86XXXX604392, the Teams Phone Number assigned to the Yealink device that also carries the SIP phone number 30001 (latter used in the Survivability UI).

          Type (Output Field)

          Called Address/Number  

          Value (Output Field)

          Enter a regular expression to replace the Teams Phone Number dialed by the PSTN user to the assigned to the SIP phone number assigned to the Yealink device with the survivability. In the example deployment, the entered expression is 30001, the Teams Phone Number assigned to the Yealink device that also carries the Teams Phone Number +86XXXX604392 (latter used in the Teams client UI).

          Transformation Table Entries and Digit Manipulation Provisioning Reference Information

        3. Click OK.

          Figure : New Transformation Table Entry for PSTN Calls to Reach Registered Yealink Device

        4. Repeat steps 1, 2 & 3 for each remaining possible registered Yealink device with both the Teams client and the Survivability (SIP) client. In the example deployment, steps 1, 2, and 3 are repeated for the Yealink device with the SIP phone number 30003.

          Figure : Completed Example New Transformation Table for PSTN Calls to Reach Registered Yealink Devices

    2. In the left navigation pane, go to Call Routing > Call Routing Table and select the Call Routing Table originally created through the use of the Easy Configuration wizard (refer to Using the Easy Configuration Wizard) template for processing calls originating from the PSTN. For our example deployment, the table requiring the new entry is From IMS .

      1. Click the Create Routing Entry ( ) icon.

      2. Enter the following values into the pop-up window:

        Table : Key Call Routing Entry Attribute Values That Must be Explicitly Submitted by User

        Field

        Required Entry

        DescriptionEnter an informative name in the text field; for our example deployment, the value is from IMS TO SIP

        Admin State

        Select Enabled

        Number/Name Transformation Table

        Select the newly created Transformation Table instance to which calls from the PSTN will be routed during survivability scenarios (i.e. when Phone System is unavailable). For the example deployment, the value is from IMS to SIP.

        Destination TypeSelect Registrar Table
        Destination Signaling GroupsSelect the newly created SIP Local Registrar-related Signaling Group to which the subtended Yealink devices are associated. For the example deployment, the value is LocalReg
        All other fieldsLeave all default values as-is for basic configuration purposes.

        Figure : Call Route Entry Attributes for Example Teams Survivability-Related Call Route Entry

        Call Routing Table Entry Provisioning Reference Information

      3. Click OK and review the new Call Routing Table Entry related to survivability in the updated PSTN-related Call Routing Table from the left navigation pane.

        Figure : Newly Created Teams Survivability Call Routing Entry in PSTN-Originated Call Routing Table

  5. Access the WebUI, click the Monitor tab. Confirm the new SIP Signaling Group instance associated with the new SIP Local Registrar instance is active. For our example deployment, the new SIP Signaling Group instance is LocalReg.

    Figure : Example SIP Signaling Group Linked to Registered Yealink Devices Shows Active

Update Yealink Teams Client Devices to Register with the SBC Edge for Survivability

Prerequisites

This section assumes the following actions are complete:

  1. Yealink client device prerequisites for Phone System Integration;
  2. SBC Edge Teams DR prerequisites and configuration.

Yealink Teams Client Device Configuration Commands

CLI (Command Line Interface) Instructions

The following general (i.e. not sample) CLI commands may be submitted via the Yealink client devices UI to enable registration with the SBC for Teams client survivability services

Yealink Teams Client Device General Provisioning Commands to Enable Survivability
features.hybrid_mode.enable=1
account.X.sip_server.1.address = <SBC IP Address>
account.X.user_name = <Username>
account.X.password = <Password>     [X ranges from 1 to 16]
features.hybrid_mode.quick_ball.enable=1     [This item is optional]

Sample commands (based on our example deployment) will appear as follows:

Yealink Teams Client Device Sample Provisioning Commands to Enable Survivability
features.hybrid_mode.enable=1
account.1.sip_server.1.address = XX.1.10.127
account.1.user_name = 30001
account.1.password = XXXXX
features.hybrid_mode.quick_ball.enable=1  
.cfg (Configuration) File Instructions

The user also has the option to submit instructions via a configuration file (*.cfg) to enable registration with the SBC for Teams client survivability services. To undertake such an operation, please refer to Yealink Teams client reference material

Instructions Must Be Repeated With Each Yealink Client

The configuration commands (whether via a configuration file or the CLI) must be repeated with each Yealink client device that is to register with the SBC Edge.

Yealink Teams Client Reference Material

Product manuals that describe the configuration and operation of the Teams clients may be found at support.yealink.com

Proceed to Testing

Testing Yealink Teams Client Local Survivability

Summary

Five key tests are required to confirm the Yealink Teams client devices can successfully offer users survivability services in the event that Phone System is unavailable, while defaulting to Teams-related services when Phone System is available. 

  1. Successful registration with the SBC via SIP;
  2. Successful call placed from the Yealink device to the PSTN via the SBC, without Phone System participation;
  3. Successful call placed from the Yealink device to another Yealink device via the SBC;
  4. Successful call placed from the Yealink device to the PSTN via Phone System;
  5. Successful call from the PSTN routed to the correct Yealink device via the SBC, when Phone System is unavailable;
  6. Successful call from the PSTN routed to the correct Yealink device when Phone System is available.

Confirm Yealink Teams Client Devices Registration with SBC Edge 

Yealink Device Confirmation

Confirm the phone icons in the device's Survivability (SIP) UI are green signifying successful registration and availability with a remote SIP server (in this case, the SBC's SIP Local Registrar). Note the 30001 phone number assigned to the Yealink device.

Figure : Yealink Device Survivability (SIP) UI with Green Phone Icons

SBC Confirmation

Access the WebUI, click the Settings tab.

  1. In the left navigation page, access SIP > Local Registrars Table.

  2. Confirm the SIP Local Registrar instance created to support survivability appears in the main body of the WebUI. For our example deployment, the the SIP Local Registrar instance is identified as LocalReg.

  3. From the SIP Local Registrar instance presented in step 2, click Registered Users

    Figure : Registered Yealink Phones with Example SIP Local Registrar

  4. Confirm the presence of the Yealink device. For the example deployment, the correct user name (phone number) is 30001 and is clearly visible in the first row of the table.

    SIP Local Registrar Registered Users Reference Information

Confirm Yealink Device Calling to the PSTN via SBC Edge

Place Call from Yealink Device Survivability UI into PSTN

  1. Access a Yealink device's Survivability (SIP) UI. In the example deployment, one such device is the 30001 client.

    Figure : Yealink Device Survivability (SIP) UI

  2. Place a call from the UI to the PSTN, and confirm two-way audio. Note the following indicators in the UI: 

    1. The green handset icon indicating a live call; 

    2. The Talking text indicating a live audio path.

      Figure : Yealink Device Displaying Active Call in Survivability Mode with PSTN Client via the SBC

From the SBC, Confirm Call Completion to the PSTN Without Transiting Phone System

Access the WebUI, and click the Monitor tab. 

  1. Expand the three signaling groups (that pertain to the survivability scenario) so all channels become visible. For our example deployment, the three signaling groups identifiers are LocalReg (the signaling group to which the Yealink devices are registered), IMS (the PSTN-related signaling group), and Microsoft Teams.

  2. Review the channel states for each signaling group, and confirm correct operation:

    1. One channel is seized (blue) in the PSTN-related signaling group (for our example deployment, the IMS signaling group). Double-click the seized channel to ensure consistency between the channel details and the call placed from the Yealink device (e.g. call direction is outgoing, call originator has the same phone number as the Yealink device, called party number is the dialed PSTN number, etc.).

    2. One channel is seized (blue) in the SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group). Double-click the seized channel to ensure consistency between the channel details and the call placed from the Yealink device.

    3. All channels remain idle (light green) in Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group).

      Figure : SBC Displaying (from the Monitor) an Active Call Between Yealink Client (in Survivability Mode) with PSTN Client via the SIP Trunk

      Signaling Group Information Available From Monitor Reference Information

Confirm Intra-Office Calling via the SBC

Place Call from Yealink Device Survivability UI To Another Yealink Device Survivability UI

  1. Access one SBC subtended Yealink device's Survivability (SIP) UI. In the example deployment, one such device is the 30001 client.

    Figure : Yealink Device Survivability (SIP) UI

  2. Place a call from the Survivability (SIP) UI to a second Yealink device, using the SIP phone number to the second Yealink device. For the example deployment, the SIP phone number assigned to the second Yealink device is 30003.

    Please use SIP Phone Number to Reach Yealink Device's Survivability (SIP) UI

    Please dial from first Yealink device the SIP phone number associated with the second Yealink device, as opposed to the phone number associated with the Teams (SIP) client. By using the SIP phone number, the test confirms that the transformation and routing table entries associated with the SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group) have been correctly provisioned for intra-office dialing when Phone System is unavailable.

  3. Answer the call from the Survivability (SIP) UI on the second Yealink device, and confirm two-way audio. Note the following indicators in the UI: 

    1. The green handset icon indicating a live call; 

    2. The Talking text indicating a live audio path.

      Figure : Yealink Device Displaying Active Call in Survivability Mode with PSTN Client via the SBC

From the SBC, Confirm Call Completion Via the SIP Local Registrar

Access the WebUI, and click the Monitor tab. 

  1. Expand the three signaling groups (that pertain to the survivability scenario) so all channels become visible. For our example deployment, the three signaling groups identifiers are LocalReg (the signaling group to which the Yealink devices arregistered), IMS (the PSTN-related signaling group), and Microsoft Teams .

  2. Review the channel states for each signaling group, and confirm correct operation:

    1. Two channels are seized and in connected state (channels will be blue) in the SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group). Double-click either seized channels to ensure consistency between the channel details and the call placed from one Yealink device to the other.

    2. All channels remain idle ( represented by the light green) in the Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group) as well as the PSTN-related signaling group (for our example deployment, the IMS signaling group).

      Figure : SBC Displaying (from the Monitor) an Active Call Between Yealink Client (in Survivability Mode) with PSTN Client via the SIP Trunk

      Signaling Group Information Available From Monitor Reference Information

Confirm Yealink Teams Client Devices Calling the PSTN via SBC Edge

Place Call from Yealink Device Teams UI into PSTN

  1. Access the Yealink device's Teams UI.

    Figure : Yealink Device Teams UI

  2. Place a call from the Teams UI to the PSTN, and confirm two-way audio. Note the active call indicators in the display.

    Figure : Yealink Phone Displaying Active Call (in Teams Mode) with PSTN Client via the SBC

From the SBC, Confirm Call Completion to the PSTN via Phone System

Access the WebUI, and click the Monitor tab. 

  1. Expand the three signaling groups (that pertain to the survivability scenario) so all channels become visible. For our example deployment, the three signaling groups identifiers are LocalReg (the signaling group to which the Yealink devices arregistered), IMS (the PSTN-related signaling group), and Microsoft Teams .

  2. Review the channel states for each signaling group, and confirm correct operation:

    1. One channel is seized (blue) in the PSTN-related signaling group (for our example deployment, the IMS signaling group). Double-click the seized channel to ensure consistency between the channel details and the call placed from the Yealink device (e.g. call direction is outgoing, call originator has the same phone number as the Yealink device, called party number is the dialed PSTN number, etc.).

    2. One channel is seized (blue) in the Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group). Double-click the seized channel to ensure consistency between the channel details and the call placed from the Yealink device.

    3. All channels remain idle (light green) in the SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group). 

      Figure : SBC Displaying (from the Monitor) an Active Call Between Yealink Client (in Teams Mode of Operation) with PSTN Client via the SIP Trunk

Confirm Survivability Operation when Phone System is Unavailable

From the SBC, Disable the Teams Phone System Signaling Group

 Access the WebUI, click the Settings tab.

  1. In the left navigation pane, go to Signaling Groups

  2. From the main display, select the check box next to the Teams Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group) and click the Out of Service () icon.

  3. Confirm that the Phone System-related signaling group is out of service, through the Down indication in the Service Status field. 

    Figure : Example Teams Phone System-Related SIP Signaling Group in Out of Service State


    SIP Signaling Group Operations Reference Information

    For details on SIP Signaling Group operation including enablement and disablement, refer to Creating and Modifying SIP Signaling Groups.

Place Call from PSTN to Yealink Device and Confirm Call Alerting on the Yealink Device's Survivability UI and the SBC's WebUI

  1. Access the Yealink device's Survivability (SIP) UI.

    Figure : Yealink Device Survivability (SIP) UI Prior to Incoming Call

  2. Place a call from the PSTN to the Yealink device, using the Teams phone number assigned to the Yealink device. For the example deployment, the Teams phone number assigned to the Yealink device with the 30003 SIP-related number is +86XXXX604393.

    Please use Teams Phone Number to Reach Yealink Device's Survivability (SIP) UI

    Please dial from the PSTN the phone number required to reach the Teams client on the Yealink device, as opposed to the phone number associated with the Survivability (SIP) client. By using the Teams client phone number, the test confirms that the transformation table entries associated with the PSTN signaling group (for our example deployment, the IMS signaling group) have been correctly provisioned for survivability routing.

  3. Confirm an incoming call is presented in the Survivability (SIP) UI. Note the alerting indication.

    Figure : Yealink Device Displaying Incoming Call from PSTN Client

  4. Access the SBC's WebUI, and click the Monitor tab. 

    1. Expand the three signaling groups (that pertain to the survivability scenario) so all channels become visible. For our example deployment, the three signaling groups identifiers are LocalReg (the signaling group to which the Yealink devices are registered), IMS (the PSTN-related signaling group), and Microsoft Teams .

    2. Review the channel states for each signaling group, and confirm correct operation:

      1. The PSTN-related signaling group (for our example deployment, the IMS signaling group) presents an alerting indication (magenta) in  a single channel. Double-click the seized channel to ensure consistency between the channel details and the call placed from the PSTN (e.g. call direction is incoming, called digits are the Teams client number of the 30003 endpoint, calling party number is the PSTN endpoint, etc.).

      2. The SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group) presents an alerting indication (magenta) in  a single channel. Double-click the seized channel to ensure consistency between the channel details and the call placed from the PSTN (e.g. call direction is incoming, called digits are the Teams client number of the 30003 endpoint, calling party number is the PSTN endpoint, etc.). 

      3. All channels remain out of service (gray) in the Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group).

        Figure : SBC displaying (from the Monitor) a call attempt from the PSTN to a Yealink device, Using a Teams client #

         

Answer Call and Confirm Connection

  1. From the Yealink device's survivability (SIP) UI, answer the call and confirm two-way audio. Note the following indicators in the UI: 

    1. The green handset icon indicating a live call; 

    2. The Talking text indicating a live audio path.

      Figure : Yealink Device Displaying Active Call in Survivability Mode with PSTN Client

  2. Access the SBC's WebUI, and click the Monitor tab. 

    1. Expand the three signaling groups (that pertain to the survivability scenario) so all channels become visible. For our example deployment, the three signaling groups identifiers are LocalReg (the signaling group to which the Yealink devices arregistered), IMS (the PSTN-related signaling group), and Microsoft Teams .

    2. Review the channel states for each signaling group, and confirm correct operation:

      1. The PSTN-related signaling group (for our example deployment, the IMS signaling group) presents a connected indication (blue) in the channel that previously presented the alerting indication. Double-click the seized channel to ensure consistency between the channel details and the call placed from the PSTN (e.g. call direction is incoming, called digits are the Teams client number of the 30003 endpoint, calling party number is the PSTN endpoint, etc.).

      2. The SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group) presents a connected indication (blue) in the channel that previously presented the alerting indication. Double-click the seized channel to ensure consistency between the channel details and the call placed from the PSTN (e.g. call direction is incoming, called digits are the Teams client number of the 30003 endpoint, calling party number is the PSTN endpoint, etc.). 

      3. All channels remain out of service (gray) in the Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group).

        Figure : SBC displaying the connected call from the PSTN to a Yealink device, Using a Teams client #

Confirm Teams Calling when Phone System is Available

From the SBC, Enable the Phone System Signaling Group

 Access the WebUI, click the Settings tab.

  1. In the left navigation pane, go to Signaling Groups

  2. From the main display, select the check box next to the Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group) and click the Enable () icon.

  3. Confirm the Phone System-related signaling group is active, through the Up indication in the Service Status field. 

Place Call from PSTN to Yealink Device and Confirm Two-Way Audio

  1. Access the Yealink device's Teams UI.

    Figure : Yealink Device Teams UI

  2. Place a call from the PSTN to the Yealink device, using the Teams phone number assigned to the Yealink device. For the example deployment, the Teams phone number assigned to the Yealink device with the 30003 SIP-related number is +86XXXX604393.

    Please use Teams Phone Number to Reach Yealink Device's Survivability (SIP) UI

    Please dial from the PSTN the phone number required to reach the Teams client on the Yealink device, as opposed to the phone number associated with the Survivability (SIP) client. By using the Teams client phone number, the test confirms that the routing table entries associated with the PSTN signaling group (for our example deployment, the IMS signaling group) have been correctly provisioned to prioritize call routing to Phone System when the latter is available for processing calls.

  3. Confirm an incoming call is presented in the Teams UI. Note the alerting indication.

    Figure : Yealink Device Displaying Incoming Call from PSTN Client in Teams UI

  4. Answer the call, and confirm two-way audio.

    Figure : Yealink Phone Displaying Active Call (in Teams Mode) with PSTN Client via the SBC

From the SBC, Confirm Call Completion via Phone System

Access the WebUI, and click the Monitor tab. 

  1. Expand the three signaling groups (that pertain to the survivability scenario) so all channels become visible. For our example deployment, the three signaling groups identifiers are LocalReg (the signaling group to which the Yealink devices are registered), IMS (the PSTN-related signaling group), and Microsoft Teams.

  2. Review the channel states for each signaling group, and confirm correct operation:

    1. One channel is seized (blue) in the PSTN-related signaling group (for our example deployment, the IMS signaling group). Double-click the seized channel to ensure consistency between the channel details and the call placed from the Yealink device (e.g. call direction is incoming, called party number has the same phone number as the Yealink device, calling party number is the PSTN number from which you made the call, etc.).

    2. One channel is seized (blue) in the Phone System-related signaling group (for our example deployment, the Microsoft Teams signaling group). Double-click the seized channel to ensure consistency between the channel details and the call placed from the Yealink device.

    3. All channels remain idle (light green) in the SIP local registrar-related signaling group (for our example deployment, the LocalReg signaling group). 

      Figure : SBC Displaying (from the Monitor) an Active Call Between Yealink Client (in Teams Mode of Operation) with PSTN Client via the SIP Trunk

Success

If all test cases are successfully completed, Teams client survivability is correctly provisioned and operational. If any test cases fail, please revisit all prerequisites and provisioning.