Ask the SIP Trunk Expert

SIP Trunking with Microsoft OCS

By Steven Johnson

SIP trunking with Microsoft (News - Alert) Office Communications Server presents a unique challenge, one that’s being faced by many enterprises today. It’s a problem with a simple solution, but one that needs to be addressed in order for SIP trunking to be possible.

Microsoft OCS operates with the customer side facing TCP/IP. TCP/IP is one of the core protocols used in unified communications and allows for the reliable, ordered transmission of data.

SIP trunks, however, use UDP (News - Alert). The solution is to provide a seamless conversion of TCP/IP to UDP. This is easily possible with an enterprise edge device, such as a SIP-capable enterprise session border controller that is designed to handle this kind of protocol conversion. As an added benefit, the edge device can also provide security for the SIP traffic (in this case, VoIP).

Ingate recently demonstrated this type of solution with an installation for Northern Michigan Substance Abuse Services Inc. NMSAS deployed SIP trunks from BBTelsys, a nationwide provider of Internet telephony and multi-dwelling unit triple play services. NMSAS was using Microsoft OCS 2007, and encountered the problem of TCP/IP-UDP incompatibility.

To address the issue, NMSAS deployed the Ingate SIParator with the Ingate SIP Trunk Software module, which works hand-in-hand with the BBTelsys service and NMSAS’ existing Microsoft OCS solution. The SIParator provided the crucial integration component necessary for SIP trunks to work with the IP PBX (News - Alert).

The industry as a whole is seeing a surge in requests for SIP trunking solutions in a Microsoft OCS environment. We’re seeing a spike in inquiries – and our VAR partners tell us the same thing. Microsoft OCS is a popular SIP-based PBX with a large installed base of users. SIP trunking is in demand as well, as a way to deploy VoIP quickly and easily, and with a very fast return on investment. Microsoft OCS users want to leverage SIP trunks now. This solution addresses the incompatibility issue – and adds significant value to the installation – immediately. IT

Steven Johnson is president of Ingate Systems (News - Alert) (