1. Start Topology Builder: Click Start, click All Programs, click Microsoft Lync Server 2010, and then click Lync Server Topology Builder.

2. In Topology Builder, in the console tree, expand the name of the site for which you want to define a Mediation Server.

3. In the console tree, right-click the Mediation pools node, and then click New Mediation Server.

4. In the Define New Mediation Pool dialog box, type the Mediation Server pool FQDN.

5. Next, do one of the following:

   • If you want to deploy multiple Mediation Servers in the pool in order to provide high availability, then select Multiple computer pool.
     
     

     Note:
     You must deploy DNS load balancing to support Mediation Server pools that have multiple Mediation Servers. For details, see the Using DNS Load Balancing on Mediation Server Pools section of DNS Load Balancing in the Planning documentation.

   • If you want to deploy only one Mediation Server in the pool because you do not require high availability, then select Single computer pool. Skip the following step.
     
     

6. If you selected Multiple computer pool in the previous step, on the Define the computers in this pool item, click Computer FQDN, type the FQDN of each server in the pool, and then click Add. Repeat this step for all other Mediation Servers that you want to add to the pool. When you have defined all the computers in the pool, click Next.

7. On the Select the next hop page, click Next hop pool, click the FQDN of the Front End pool that will use this Mediation Server pool, and then click Next.

8. On the Select an Edge Server page, do one of the following:

   • If you want to provide PSTN connectivity to external users enabled for Enterprise Voice, under Select Edge Pool used by this Mediation Server, click the FQDN of the Edge Server pool that will use this Mediation Server pool to provide PSTN connectivity to those external users, and then click Next.
     
     
   • If you do not plan to enable external users for Enterprise Voice or if you do not want to provide PSTN connectivity to users when they are outside the internal network, click Next.
     
     

9. On the Specify PSTN gateways page, do one of the following:

   • To specify a peer (gateway, PBX, or Session Border Controller) that you previously defined but have not yet associated with any Mediation Servers, click the peer FQDN or IP address in the list, and then click Add. Skip the next step.
     
     
   • To associate an additional peer with this Mediation Server pool, click New, and then continue to the next step.
     
     

10. In the Define new IP/PSTN Gateway dialog box, do the following:

    • Click Gateway FQDN or IP Address, and then type the peer’s FQDN or IP address.
      
      
    • Optionally, click Listening port for the IP/PSTN gateway, and then type the listening port that the peer will use for SIP messages from the Mediation Server pool. (By default, the ports are 5066 for TCP and 5067 for TLS on a gateway, PBX, or SBC. On a Survivable Branch Appliance at a branch site, the default ports are 5081 for TCP and 5082 for TLS.
      
      
    • Under Sip Transport Protocol, click the SIP transport protocol that the peer uses.
      
      

      Note:
      For security reasons, we strongly recommend that you deploy a peer to the Mediation Server that can use TLS.

    When you are finished, click OK.

11. For the peer to which you want this Mediation Server pool to route calls from Microsoft Office Communications Server 2007 R2 Enterprise Edition or Standard Edition servers to the PSTN, click Make Default.

12. When you are finished associating one or more peers to the Mediation Server pool, click Finish.

    Note:
    Before you proceed to the next step in the Enterprise Voice deployment process, ensure that the Mediation Server pool and any computer that you added to the pool are running using the FQDNs that you specified.

13. Next, follow the procedures in Publish the Topology in the Deployment documentation to add the Mediation Server to the topology. You must publish your topology each time you use Topology Builder to build or modify your topology so that the data can be used to install the files for servers that are running Lync Server. Then continue to the next steps to modify the listening ports on the Mediation Server, if necessary.

1. Start the Lync Server Management Shell: Click Start, click All Programs, click Microsoft Lync Server 2010, and then click Lync Server Management Shell.

2. By default, the SIP listening ports on the Mediation Server are 5070 for TLS traffic from Lync Server, 5067 for TLS traffic from peers (gateways, PBXes, or SBCs). Optionally, run the following cmdlet to modify the SIP listening ports on the Mediation Server (replacing the value of the parameters with the service identity and ports for your topology):

   	Copy Code
   Set-CsMediationServer medsvr.contoso.net -SipServerPort 5061 -SipClientTlsPort 5062

   The SipServerPort parameter specifies the listening port for SIP messages from Lync Server and the SipClientTlsPort specifies the listening port for SIP messages from the gateway that are sent using the TLS transport protocol. Obtain the value for the Identity parameter by running:

   	Copy Code
   Get-CsService

Next, install the files on each Mediation Server in the pool by following the procedures in Install the Files for Mediation Server.