Posted in AudioCodes, Lync Server 2013, Skype for Business

AudioCodes AA – ACD call cannot transfer to any internal SfB User




  • AudioCodes Auto-Attendant is installed as virtual machine inside the SBA.
  • SBA is associated to a SfB Enterprise Edition in Central Pool.
  • AudioCodes AA configured with Automatic Call Distribution (ACD) in Call Work Flow
  • When a PSTN caller calls to AA IVR and chose ACD option (e.g. transfer to Receptionist), Receptionist answer the call but when it tries to transfer to any internal SfB user within the branch site, the transfer failed.

Errors on SfB logs captured on SBA

  • The call cannot be transferred
  • SIP/2.0 504 Server time-out
  • ms-diagnostics: 1038;reason=”Failed to connect to a peer server”;ip-address=”″;peer-type=”InternalServer”;winsock-code=”10061″;winsock-info=”The peer actively refused the connection attempt”;source=”SfBPoolinCentralSiteFQDN”
  • SIP/2.0 400 Bad Request



Open TCP port 15001 from SfB servers in Central office to AudioCodes Auto-attendant.

SfB requires that all servers, that receive REFER and start a new call as result of the REFER, have access to the referring server, for authenticating the referred-by header.

In the case above all servers should have access to AudioCodesAA.local:15001


Thanks to AudioCodes R&D, they found the solution!

But this port is not on Firewall requirement on AC document so we have requested it to be added.





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