Troubleshooting Lync Edge 101

We installed a "simple" Lync Edge system with collocated Front-End and Mediation server and Enterprise Voice connected to the PSTN via a Nortel CS1000 PBX.

After configuring (among other things)

• Internal DNS
• External DNS
• Routing on the EdgeServer
• Internal Certificate
• External Certificate
• Public IP addresses
• Primary DNS suffix on the EdgeServer
• Open ports on the Internal Firewall
• Open ports on the External Firewall
• The mediation server to find the PBX
• The PBX with a SIP Trunk
• The topology, exported it and imported it on the EdgeServer
• Users with external access, enterprise voice and a valid line URI
• A Voice Policy, PSTN Usage and Route
• Automatic login internally and externally

and checking the configuration a few times, we could call…

External Lync <---> Internal Lync

Internal Lync <---> Mobile Phone

But not…

External Lync  ---> Mobile Phone

Mobile Phone  <---  External Lync

The signalling from the External Lync client to the Mobile phone went through, the phone would ring and we could answer the call. On the external Lync client the status shifted from "Calling" to "Connecting call", where it sat for a few seconds and finally displayed "Call failed due to network issues". This indicated that the signalling path were working fine and the problem was happening as the system tried to setup the media stream.

We then used the Lync Server 2010 Logging tool to find this error message:

"Call failed to establish due to a media connectivity failure when one endpoint is internal and the other is remote"

Which led us to this post on the Lync forums: Incoming PSTN call to external user fails to connect

After investigating the logs some more we saw that the mediation server tried to establish a media path straight to the external client!? Did it not know we had an edge? - No, it actually did not!

After looking in the Lync Control Panel / Topology / Standard Edition / Mediation Server, we noticed that the EdgeServer setting were "Not Set"

With Power Shell we could check this with the following command:

Get-CsService -MediationServer

Identity                 : MediationServer:standard.kressmark.com

Registrar               : Registrar:standard.kressmark.com

EdgeServer            :

SipServerPort         : 5070

SipClientTcpPort     : 5060

SipClientTlsPort      : 5067

AudioPortStart        : 49152

AudioPortCount       : 8348

DependentServiceList : {PstnGateway:10.10.10.40}

ServiceId             : 1-MediationServer-4

SiteId                 : Site:Stockholm

PoolFqdn             : standard.kressmark.com

Version               : 5

Role                   : MediationServer

Also, in the Lync Control Panel / Topology / edge.kressmark.com / Edge Server / Dependents, we could only find “Registrar:…” and “ConferencingServer:…” and no "MediationServer:....

So our Mediation Server did not know we had an Edge, and the Edge server did not know about the Mediation server. My guess is that internal calls to PSTN worked simply because the Mediation server were collocated with the Standard server.

However, we used the following command to make things right:

Set-CsMediationServer -Identity "MediationServer:standard.kressmark.com" -EdgeServer edge.kressmark.com

And after restarting the Lync control panel it displayed correct data, and calls from the external Lync client via the collocated mediation server to PSTN worked (and the other way around as well!)

Puh!