Configure media bypass global settings in Lync Server 2013 to use site and region information


Topic Last Modified: 2012-09-21


This topic assumes that you have already configured media bypass for any trunk connections from the Mediation Server to a peer (a public switched telephone network (PSTN) gateway, an IP-PBX, or a Session Border Controller (SBC) at an Internet Telephony Service Provider (ITSP) for a specific site or service for which you want media to bypass the Mediation Server.
This topic also assumes that you have defined all central sites and branch sites in Topology Builder in a way that matches the network region, network site, and subnet configuration that you performed according to the steps in Create or modify a network region in Lync Server 2013, Create or modify a network site in Lync Server 2013, and Associate a subnet with a network site in Lync Server 2013. If they do not match, then media bypass will not succeed.

In addition to enabling media bypass for individual trunk connections associated with a peer, you must also configure global settings. If you use the steps in this topic to configure global settings for media bypass, the assumption is that one or both of the following situations affects your configuration:

  • You do not have good connectivity between Lync Server endpoints and any peers for which you configured media bypass on the trunk connection.

  • Call admission control (CAC) for bandwidth management is enabled.


    For details about the considerations for both call admission control and media bypass, see the "Call Admission Control of PSTN Connections" section in Media bypass and Mediation Server in Lync Server 2013 in the Planning documentation.

Network region and network site information is shared between call admission control and media bypass advanced Enterprise Voice features when both are enabled. Therefore, if you have already configured call admission control, you are not required to use the following procedure to edit the site and region information specifically for media bypass. Follow the steps in this procedure if you have not yet configured network regions and sites for call admission control, and you want to change media bypass settings.

Or, follow these steps if you want to use site and region information in making the bypass decision, but have no intention of enabling call admission control. In such a case, bandwidth restricted links will still need to be represented through network intersite policies, as described in Create network intersite policies in Lync Server 2013. The actual bandwidth constraints are not as important in this case, because call admission control has not been enabled. Instead, these links are used to partition subnets to specify those that have no bandwidth limits and can, therefore, employ media bypass. Note that this is also true when call admission control and media bypass are both enabled.

Furthermore, for bypass to work properly there must be consistency between a site as defined in Topology Builder and as it is defined when you configure network regions and network sites. For example, if you have a branch site that you defined in Topology Builder as having only a PSTN gateway deployed, then that branch site must be configured with an Enterprise Voice policy that enables branch site users to have their PSTN calls routed through the PSTN gateway at the branch site.

To Configure Site and Region Information for Media Bypass

  1. Open a browser window, and then enter the Admin URL to open the Lync Server Control Panel. For details about the different methods you can use to start Lync Server Control Panel, see Open Lync Server 2013 administrative tools.

  2. In the left navigation bar, click Network Configuration.

  3. Double-click the Global configuration in the table.

  4. On the Edit Global Setting page, select the Enable media bypass check box.

  5. Click Use sites and region configuration.

  6. If necessary, select the Enable bypass for non-mapped sites check box.


    Select this check box only if you have one or more large sites associated with the same region that do not have bandwidth constraints (for example, a large central site), but you also have some branch sites associated with the same region that do have bandwidth constraints. When you enable bypass for non-mapped sites, configuration is streamlined in that you specify only the subnets associated with the branch sites, rather than needing to specify all subnets associated with all sites. We recommend that you do not select this check box if call admission control is enabled.

  7. Click Commit.

Next, add subnets to the network site, as described in Associate subnets with network sites for media bypass in Lync Server 2013. (The actual procedures for associating subnets with network sites are described in Associate a subnet with a network site in Lync Server 2013.) After you associate all subnets with network sites, media bypass deployment is complete.


If you have not already created network regions and network sites, you must first create those before you can proceed with media bypass deployment. For details, see Create or modify a network region in Lync Server 2013 and Create or modify a network site in Lync Server 2013.