This article originally appeared in the November 2012 issue of INTERNET TELEPHONY.

End users, VARs and service providers are all facing the interoperability challenge: for years deployments have been dependent on what equipment was available at the time, price point and capability. Now that technology and market demand are in sync, the challenge has been integrating the hardware and software in which we’ve invested so heavily, to have them all come together to enable unified communications.

One problem with interoperability is the many implementations of SIP. Session initiation protocol offers multiple ways to perform the same function. Each vendor and/or service provider may use different but compliant methods to perform the same function within the protocol.

These variations may be slight, but in the end can prove to be a significant stumbling block in deployments.

They also affect security. Opportunities for hackers, spoofers and the like are easy to come by when there are inconsistencies between the SIP-enabled PBX (News - Alert) and the ITSP. Leading IP PBXs and ITSPs are aggressively conducting interoperability testing; make sure your equipment and service providers have demonstrated successful interoperability with one another.

Pave the way for interop by using products that strictly adhere to the protocol and do not include vendor-specific variations that are not covered by the SIP standard. There are a number of advantages vendors can leverage with SIP that benefit security, advantages that come into play only when the protocol is strictly maintained.

This also positions you well in planning your future network.  

Specific to SIP trunking is the SIPconnect solution, developed by the SIP Forum (News - Alert) to provide a common method for enterprises to connect to a SIP trunking service provider using standard SIP messages consistently across all vendors. SIPconnect is a major step forward toward standardizing interoperability among all of the components of a SIP trunking implementation but will take some time to be commonplace.

Even with these strides, there are many issues that won’t be resolved in the near term, and the best steps to take in implementing SIP, SIP trunking and unified communications are to install an enterprise session border controller at the edge of the network. The E-SBC normalizes the SIP signaling between the SIP-enabled PBX and the ITSP, allowing the enterprise to successfully connect to SIP trunking service providers quickly, easily and securely.

Steven Johnson is president of Ingate Systems (News - Alert) (www.ingate.com).