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Lync 2013 503 Service Unavailable

While working on setting up a SIP Trunk for Lync 2013, I kept encountering an error in my SIP traces. This was true if Lync was using a gateway (in this case and AudioCodes Mediant 1000B), or was connecting directly to the ITSP.

The error in the trace was “503 Service Unavailable” and the detail showed:

10014;reason=”An internal exception received while processing the incoming request”;component=”MediationServer”;Exception=”An exception has been thrown in processing BeginApplyMediaLines”

Everything with the topology and trunk configuration looked correct and most Lync services were behaving correctly. It’s that “most” that should have been my clue. Application sharing to federated partners wasn’t working either, even though IM and presence were.

The resolution for both turned out to be incredibly simple. The Front End servers could not resolve the name of Edge Pool.

Now, I can understand why that would impact federated application sharing, but outbound calls as well? That was a bit surprising.

So, don’t forget to ensure name resolution and connectivity to/from your Lync Front End and Edge Pools. It’ll make your life easier in the long run.

Shane Skriletz, PEI

One Comment

  • isj50 says:

    Thanks, Shane.
    Your post pointed us to the cause of our issue: there was a temporary DNS outage which resulted in our edge pool address being unresolvable and our PSTN calls started to drop. By the way, we’re on Skype for Business 2015.

    More details for troubleshooters in the future:
    We saw the same SIP 503 / “ms-diagnostics: 10014” error. Further CLS logging revealed a warning confirming the issue:
    MediationServer,MediaSessionAgent.GetConnectivityServersAsyncResult.GetHostEntryCallback:mediasessionagent.cs(8121)
    GetConnectivityServersAsyncResult : Caught SocketException (No such host is known) resolving media relay host name

    And here is the whole error message from Snooper:
    ============================================================
    TL_ERROR(TF_COMPONENT) [\]3E15C.429C0::11/14/2016-10:02:53.463.000045E8 (MediationServer,GatewayCall.FinishApplyMediaLineDescriptions:gatewaycall.cs(1620)) [9710071]
    9710071Exception: System.Exception: An exception has been thrown in processing BeginApplyMediaLines —> Microsoft.RTC.MediationServerCore.MediaException: GatewayStream Initialize error. —> System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
    Parameter name: No primary servers configured
    at Microsoft.Rtc.Internal.Media.RtpEndpoint.ConvertRTPConnectivityServerInfo(Collection`1 value, IceServerArray_t* pIceServerArray)
    at Microsoft.Rtc.Internal.Media.RtpEndpoint.ValidateConnectivityServers(Collection`1 value)
    at Microsoft.Rtc.Internal.Media.RtpEndpoint.set_ConnectivityServers(Collection`1 value)
    at Microsoft.RTC.MediationServerCore.GatewayStream.BeginInitialize(ApplyMediaLineWorkitemAsyncResult applyMediaLineResultWorkitem, MSMediaLineDescription mLineDescription, Boolean bSdpLessRetargeting)
    — End of inner exception stack trace —
    at Microsoft.RTC.MediationServerCore.GatewayStream.BeginInitialize(ApplyMediaLineWorkitemAsyncResult applyMediaLineResultWorkitem, MSMediaLineDescription mLineDescription, Boolean bSdpLessRetargeting)
    at Microsoft.RTC.MediationServerCore.GatewayMedia.ProcessApplyMediaLineWorkItem(List`1 mediaLines, ApplyMediaLineWorkitemAsyncResult applyMediaLineResultWorkitem, RetargetingSettings bRetargetingSettings, Dictionary`2& gatewayStreamToDescriptionDic)
    at Microsoft.RTC.MediationServerCore.ApplyMediaLineWorkitemAsyncResult.Microsoft.Rtc.Collaboration.AudioVideo.IWorkitem.Process()
    — End of inner exception stack trace —
    at Microsoft.RTC.MediationServerCore.GatewayCall.FinishApplyMediaLineDescriptions(IAsyncResult ar)NULL
    ============================================================

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