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Overview - Supplementary Services

The SBC Edge supports IP PBX supplementary services per RFC 3261 for incoming and outgoing signaling groups for the following SIP clients (phones or SIP PBXs) and SIP clients to legacy interfaces (such as CAS, FXS, ISDN). The following Supplementary Services are supported:

  • Call Transfer
  • Call Hold
  • Call Forward
  • Call Waiting
  • Call Park/Pickup

The section below details the features supported, as well as provides links to detailed information.

What does the SBC Edge Support?

The SBC Edge supports the following IP PBX Supplementary features:

Figure : Supplementary Services Supported in SBC

Supplementary ServiceService Initiated BySBC 1000/2000SBC SWe Lite
Call Transfer

Analog FXS, SIP endpoints

Call HoldAnalog FXS, SIP endpoints(tick)(tick)
Call WaitingAnalog FXS, SIP endpoints(tick)(error)
Call ForwardAnalog FXS, SIP endpoints(tick)(error)
Call Park/PickupSIP only(tick)(tick)
Music on HoldAnalog FXS, SIP endpoints(tick)(tick)

How SBC Edge Supports Supplementary Services

The following table details how the SBC Edge supports each supplementary services type.

Figure : Supplementary Services - Call Function

Supplementary ServiceFunctionAnalog FXS Function

SIP to SIP Function (Agent Type configured as Back to Back User Agent)1


SIP to SIP Function (Agent Type configured as Access Mode)1


Call Transfer

Call transfer puts an active call on hold to get a dial tone and start dialing the phone number that the active call will be transferred to.

The SBC supports two transfer modes:

Attended. When one of the two parties involved in a call transfers the call to a third party after consulting with the third party.

Unattended.When one of the two parties involved in a call transfers the call to a third party without consulting with the third party.

  • Blind and Consultative transfers handled by the SIP REFER method.
  • New INVITE generated towards the transfer target.
  • SBC does not proxy or send SIP REFER to the transferee.


  • SBC does not provide Supplementary Services feature; it relays all messages to the end device.
  • End device is responsible for handling the appropriate call/supplementary services features.

Call Hold

Call Hold puts an active call on hold.


  • Initiated by an analog phone connected to an FXS port.
  • The user can perform a flash hook (quickly depressing button on the handset cradle) at any time to put the active call on hold, and another flash hook to resume the call.
  • To configure on the SBC, refer to Managing Supplementary Service Profiles.2
  • If MOH is configured, it plays the MOH towards the device being put on hold.
Call Waiting

Call Waiting allows a party involved in exiting a call to receive another call. The receiving party is notified of the new call either by an in band tone or display notification or both.

  • End-device functionality.
  • Routes second call to the SIP end device. If the SIP device supports call waiting, it will alert the called party either through in band tone or display or both.
Call Forward

Call Forward enables a received phone to forward calls to another destination.


  • Enables support to an analog phone connected to an FXS port.
  • For incoming calls, there is a short ring before the call is forwarded.
  • Configured via analog phone connected to an FXS port or via SBC's WebUI.2 For configuration on the SBC, refer to Creating and Modifying CAS Signaling Groups.2
  • Receives a SIP 3XX response from the end device and redirecting/forwarding the INVITE to the new location as defined in RFC 3261.

Call Park/PickupCall Park/Pickup enables an external device to pick up an existing call (in alerting or connected state) on the SBC.

Configuration is dependent on the end device.

  • Handles an inbound SIP INVITE with Replaces Header from the phone to pickup a parked call.
  • Configured on an external device (i.e., multiple SIP phones are configured to be part of a workgroup; the workgroup properties can allow the phones to pick up each other's calls).

Music on Hold

Music on Hold enables music to be played when a user is on hold.


  • FXS port initiates call hold (which results in the SBC Edge playing MOH toward the other party).
  • FXS port can act as a live music source. For configuration, refer to Configuring the Media System.

  • Plays on all the SBC interfaces and SIP calls through the SBC Edge, but only on a SIP endpoint.
  • For configuraiton on the SBC, refer to Configuring the Media System.

1 For details on configuring the Agent Type, refer to Creating and Modifying SIP Signaling Groups.

2 WebUI configuration applies to SBC 1000/2000 only.