Current Limitations

This section describes the current limitations in the SIP Server integration with Microsoft Lync / Skype for Business.

Multiple Front End Server support on the same subnet

The Multiple Front End Server support of UC Connector depends on the mechanism used by the Windows host's DNS Client to resolve the pool's Front End IPs.

First pick from the set of resolved IPs is the default DNS Client behavior in Windows 2003 Server, usually with the DNS Server re-ordering in round-robin fashion.

Windows 2008 R2 Host DNS Client complies with the RFC3484 Rule of Destination Address selection; the unreachable destinations are automatically avoided. This is limited to hosts within the same subnet.

Genesys UC Connector is limited to provide Front End Failover support when provisioned on a Windows 2008 R2 host, and has to be in the same subnet as the Lync.

IP Phone support

Genesys only supports the use of the Lync or Skype for Business desktop clients as soft-phones for voice communication.

This Genesys deployment does not interoperate with Lync- or Skype for Business-supported IP hard phones, such as Polycom CX series. Use of these phones has the following limitations:

• The AnswerCall option through Interaction Workspace cannot be used to answer the call on the a physical phone.
• 1pcc call handling, such as transfers and conference done using the IP phone, does not coordinate with the call control on the Genesys suite. Only Workspace-based 3pcc call control through should be used.

Early Media support should be disabled

When a SIP User Agent supporting Early Media (such as the SIP Server) contacts the Mediation Server, the Mediation Server does not apply Media bypass condition for the call. The Mediation Server responds with a 183 Session Progress containing its own SDP, Required:100rel and an RSeq header. The SIP Server sends a RAck in the PRACK.

The Mediation Server contacts the Front End Server to reach the Lync/Skype for Business Client— this call is Early Media enabled. When the Client responds with its Early Media SDP, the Mediation Server attempts to update the UAC with the Client's Early Media SDP; however, the 2nd 183 Session Progress response does not contain an incremented RSeq header value—the UAC doesn't process it. This is not compliant with the RFC 3262 guideline.

As a result, SIP early media does not work with the Lync or Skype for Business Mediation Server, and should be disabled as a SIP Server option.

Conversation Extension Window

The Conversation Extension Window functionality does not work when using the Skype For Business client on the Knowledge Worker desktop.