SIP DID issues

m-ketchum · ‎05-15-2009

I'm deploying a UC520 using Broadvox SIP trunk service and DID's

One main number is used for registering the trunk.

Problem:

All invites of incoming calls use the main number in the URI. The DID's use the FROM field as the DID differentiator. The problem is that the UC520 is routing all calls based on the number in the invite and not the DID in the FROM field.

Is there any way to make the UC520 look at the FROM field instead?

Thanks,

Mike

Maulik Shah · ‎05-15-2009

I think you mean the actual called number is in the To field, not From field of the SIP INVITE. The answer is no this is not supported because:

- This is not in line with RFC3261 usage of the To header and has potential to cause confusion as the To header can be changed if calls are forwarded

- There is a SIPConnect forum (which includes all the major telecom vendors) that has a standard which states the below:

The To header field of a SIP request generated by the SP is normally populated in the same format, and with the same URI, as the Request-URI, as specified in sections 10.1.1 above. However, there may be cases, such as a prior redirection, where the To header field URI does not contain the desired destination. As such, the SIP-PBX MUST NOT rely on the contents of To header field for routing decisions, but MUST use the Request-URI instead.

Some notes from the web as well:

https://lists.cs.columbia.edu/pipermail/sip-implementors/2009-April/022482.html

You need to ask Broadvox to change their methodology to be more in line with the industry standard and the SIP standard.

m-ketchum · ‎05-15-2009

Yes, that is exactly what I was asking...thank you for reading into it...been a long morning.

Ok, cool, that is what I figured based on some research. Thank you for confirming.

Have a great weekend!