[Spce-user] sometimes with t.38 spce is getting confused whic packets to send T38 UDP on

Matthew Ogden matthew at tenacit.net
Thu Oct 8 10:17:22 EDT 2015

Hi All

I have a case where T38 fax is negotiated with a reinvite , and things are
a bit odd

Call flow is

subscriber -> spce -> peer  (and other things I cant see)

ReINVITE is made by the peerside.

The peer does a port change on the reinvite, and SPCE keeps the port the
same on its side.
The subscriber also keeps its ports the same.

Then things get a little strange. The peer (for whatever reason), starts
sending from the original port, and SPCE relays this (as it turns out, to
the original subscriber port), so from the perspective of the subscriber,
its seeing conflicting messages but coming from the same port of SPCE,
destined to the same port.

Shouldn't the original RTP port be closed off once the ReINVITE gets an OK?

Kind Regards

*Matthew Ogden*



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