If you have been following our series of webinars on SIP applications, you’ll surely agree that as an industry, we’ve made some great progress in building new networks and applications leveraging the power and features of SIP. Both enterprise and service provider solution developers have eagerly adopted SIP as the cornerstone for call control and media management due to its flexibility, expandability and standards adoption.

However, these same attributes frequently become a burden for the solution engineers that are trying to deploy SIP solutions in the real world. Whether it is trying to connect an IP-PBX to a SIP Trunking vendor, a contact center to an IP-PBX, or two service provider networks together in a peering relationship – the current state of true SIP interoperability is “spotty” at best.

The Interoperability Challenge

It seems that universal SIP interoperability is a goal that is always just out of reach.

In some cases, the incompatibility is purely technical. Decisions about implementations of SIP were made from the myriad of options within the RFC3261 specification that are incompatible with each other. Examples: There are at least four different ways to transport DTMF, three different ways to transport fax, and dozens of voice coder formats. For two SIP-based systems to interoperate, all of the SIP options must be in alignment.

In other cases, the incompatibility is more about business. There are many cases where two competitors systems “should” work together, but getting both sides to commit to exhaustive interoperability testing is impossible. “Why should we help a competitor get their system to work with ours?” is a common reply to interoperability requests.

Efforts to standardize the interfaces between systems have been stymied by rigid and already aging existing equipment, corporate pride and stubbornness. Beyond this, there is a strong community of developers that oppose “fixing” the SIP standard and believe that limiting future change will cap growth and prevent opportunities to extend SIP in the future.

IP-to-IP Mediation - The Solution

Leveraging AudioCodes’ unique interoperability experience with a wide array of SIP applications and devices, we have introduced a powerful IP-to-IP Mediation with our most recent 5.4 version of gateway software. With this feature set, AudioCodes is able to close the gap between many currently incompatible SIP systems.