"SIP/2.0 504 Cannot connect to gateway. Socket error: TimedOut" error message when a PSTN call is routed to a Mediation server in Lync Server 2010


Consider the following scenario:
  • You have a Microsoft Lync Server 2010 environment that has more than one Mediation server and a Public Switched Telephone Network (PSTN) gateway deployed. The Mediation servers are configured to use dual Network Adapters.
  • A Mediation server cannot connect to the PSTN gateway because of a network issue that is specific to the Mediation server.
  • You call a PSTN number by using Lync 2010.
  • The call is routed to the Mediation server.
In this scenario, the Outbound Route application in Lync Server 2010 does not route the calls to a different Mediation server. Additionally, the Mediation server returns the following error message:

SIP/2.0 504 Cannot connect to gateway. Socket error: TimedOut


To resolve this issue, install the following cumulative update:

2502810 Description of the cumulative update for Lync Server 2010, Mediation server: April 2011


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Article ID: 2539642 - Last Review: Apr 20, 2011 - Revision: 1