[Spce-user] No rewrite on T.38 INVITE

Andrew Pogrebennyk apogrebennyk at sipwise.com
Mon Aug 17 10:58:06 EDT 2015

On 08/17/2015 03:39 PM, Tristan Delsol wrote:
> They state that they don't support that format for the contact header.
> They have it in the specs for the interconnect that the contact header
> can only contain the following:
> sip:+«ISN»@«ip-address/URL»:«port» with optional user=”phone”, so for
> example sip:+31703434343 at domain.net:5060;user=”phone”.
> Where
> ISN: International Subscriber Number
> port: UDP portnumber;
> URL: Uniform Resource Locator: domain name;
> Is it possible I can adjust the contact header for this kind of request
> to keep the format as needed?

Unfortunately this is not something you can easily achieve, but if you
have some understanding of kamailio config scripts you can try to modify
and disable the Contact masking completely, e.g. comment out all calls

Then each side will receive the internal IP of b2b as Contact:
sip:, which exposes your topology a bit to outside but
still doesn't break the protocol. But we are not sending the number part
which might be a problem for them (they didn't say that the number part
is optional). Sorry I can't help you out more at this time.


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