When calling some foreign numers Lync server CANCEL the call when it is in progress. Network sniff shows that the call is terminates after 10 sec.

This is a default value of the Lync Routing engine. The value is located in “c:\program files\Microsoft Lync Server 2010\Server\Core\OutboundRouting.exe.config”

SOLUTION:Replace value “FailOverTimeout” value 10000 with a value of 20000. Reboot server. Remember to do this on every frontend server that is involved. You will have to reboot involved servers for this to be activated

<configuration>
    <appSettings>
      <add key=”FailOverTimeout” value=”20000″/>
      <add key=”MinGwWaitingTime” value=”1″/>
      <add key=”MaxGwWaitingTime” value=”20″/>
      <add key=”FailuresForGatewayDown” value=”10″/>
      <add key=”FailuresForGatewayLessPreferred” value=”25″/>
      <!– Valid values are between 5 and 600 –>
      <add key=”HealthMonitoringInterval” value=”300″/>
      <!– Valid values are between 60 and 3600 –>
      <add key=”GatewayStateReportingInterval” value=”1800″ />
  </appSettings>
</configuration>