Like Microsoft® Office Communications Server (OCS) 2007, which has a tremendous installation base of users employing OCS SIP-based communications, Microsoft Lync 2010 is not natively compatible with SIP trunking.

Why is this so? Microsoft OCS and Lync operate with the customer side facing TCP (Transmission Control Protocol)/IP. TCP/IP is one of the core protocols used in Unified Communications (UC) and allows for the reliable, ordered transmission of data. SIP trunks, however, use UDP.

Enterprise Session Border Controllers (E-SBCs) can solve this problem. They sit at the edge of the network to provide control over the SIP traffic. Traditionally they were seen as just providing firewalling protection – the security – for SIP-based voice networks. Today’s E-SBCs provide that security, which is absolutely a critical function, and have evolved to serve as a crucial element in enabling SIP deployments.

E-SBCs can provide a seamless format conversion of TCP/IP to UDP, working hand-in-hand with the ITSP service and Microsoft Lync 2010 solution.

Ingate recently worked with Northern Michigan Substance Abuse Services, Inc. (NMSAS) in a great example of how the Ingate E-SBC (the SIParator), working hand-in-hand with SIP trunks from BBTelsys, provided the critical integration necessary for SIP trunks to work with Microsoft OCS.

NMSAS was using Microsoft OCS 2007 to converge their voice and data. The SIParator enabled SIP trunking by resolving Network Address Translation (NAT) traversal of SIP traffic. It provided a seamless format conversion of TCP/IP to UDP, working hand-in-hand with the BBTelsys service and NMSAS’ existing Microsoft OCS solution.

Working with Ingate’s SIP Trunk Software module, it also normalized the SIP signaling between the IP-PBX, in this case the Microsoft OCS server, and the BBTelsys service, solving interoperability issues. The SIParator also secured the voice-over-IP (VoIP) calls made over the SIP trunk.

As Microsoft Lync 2010 gains marketshare enterprises (and service providers) can be confident that with the right E-SBC not only will the transition from OCS to Lync go smoothly, but interoperability between the IP-PBX (most any IP-PBX) and SIP trunk service will be resolved as well.