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As part of MS Teams Direct Routing, Local Media Optimization enables you to keep media localized to your network. Such optimization helps avoid quality issues, toll charges, and possible security concerns.

The SBC supports Local Media Optimization with the PSTN connected to a hub, as summarized below:

  • The SBC trunk group for the MS Teams side can have two media IP interface groups, configured using the following parameters:

    • mediaIpInterfaceGroupName – To configure the primary interface group, use internal/private media interface address.

    • mediaIpSecondaryInterfaceGroupName – To configure the secondary interface group, use external/public media interface address.

  • The media interface addresses (primary/secondary) used for a call are based on the new headers: X-MS-MediaPath, and X-MS-UserLocation.

  • For calls that have media anchored on the SBC, the SBC selects media interface using either public (external) or private (internal) interface address, based on the X-MS header contents received from MS Teams.

  • A call can start with primary (internal) media interface address in the Signaling SDP, but change to using secondary media interface address, if the SBC receives appropriate indications in the X-MS headers from MS Teams.

Reference Network Architecture

Using the SBC's capability of relaying media using internal IP addresses, the MS Teams user and the SBC can exchange media over internal network. For example, you can use WAN connection for media exchange, and avoid the internet. This approach often results in a better voice quality and lower latency.

MS Teams - SBC - Local Media Optimization

Call Flows

The following images illustrate the ingress and egress call flows, based on the content of the header X-MS-UserLocation.

Call Flow - Ingress - X-MS-UserLocation: Internal

Call Flow - Ingress - X-MS-UserLocation: External

Call Flow - Egress - X-MS-UserLocation: Internal

Call Flow - Egress - X-MS-UserLocation: External

Configure SIP Trunk Group towards Teams


Mandatory! You must capitalize SIP Trunk Group names.

Create a SIP Trunk Group for the Teams side.

  • Configure LIF1 as the internal IP.
  • Configure LIF2 as the external IP.

% set addressContext default zone TEAMS_ZONE sipTrunkGroup TEAMS_TG mode outOfService state disabled
% set addressContext default zone TEAMS_ZONE sipTrunkGroup TEAMS_TG media mediaIpInterfaceGroupName LIF1
% set addressContext default zone TEAMS_ZONE sipTrunkGroup TEAMS_TG media mediaIpSecondaryInterfaceGroupName LIF2
% set addressContext default zone TEAMS_ZONE sipTrunkGroup TEAMS_TG mode inService state enabled
% commit

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