TDM to H.323 to SIP and back again

We’re working on an interesting project for a medium sized cable company. They currently have a Nortel CS1000 located at their corporate office and we are tasked with implementing a SIP based IVR solution from Holly Connects for them.

The problem is that the version of the CS1000 they are currently running does not support SIP. The customer has plans to upgrade the switch at some point, but times being what they are – it’s not in the budget right now. So, how do you hook a SIP based IVR up to a Nortel CS1000? Well, the CS1000 does support H.323. And it just so happens that we have a product capable of handling an H.323 to SIP translation. We use our FlexxGate product for several different applications where we’re taking TDM to SIP. Support was already in place to convert H.323 from Avaya to SIP, so Nortel CS1000 H.323 to SIP wasn’t hard to implement.

But, there was a wrinkle – we don’t just need to bridge the H.323 to SIP divide, we also have to work with a CTI IVR product from Syntellect (formerly Envox) called CTConnect. One of the things we need to is have the original call reference ID from the CS1000 available to the IVR application in order for the CTI functionality to work properly. Through some fancy footwork one of our developers was able to extract the call reference ID from the Q.931 messages coming in on H.323 and pass it along to the IVR in the form of a custom SIP header.

And now we are able to place a call from a landline, into the Nortel CS1000, out to FlexxGate on h.323, preserve the call reference ID, and pass the call on to the IVR via SIP. A lot of moving parts, but it’s working very well.

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Posted by eckoh at 6:01 PM on Jan 30, 2012


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