[Freeswitch-users] INVITE via another SIP proxy

[Ingmar Schraub]

Hi,

I ran into a problem today and I thought I should place the question
here and hopefully someone has an idea what's going on.

FYI, I am using GIT from November 15th 2010.

Here is my problem:

My SIP phones are all on the LAN. I can register them, make calls, etc.
all work fine. I run FS with "-nonat".

Now, when I add another SIP proxy in the chain, let my phones register
with FS via that proxy, everything is still fine. No issues with
registrations.

The problem is, that INVITEs do not work. FS rejects them with "400 Bad
Request".

I turned on SIP tracing on FS to see how the SIP messages look like and
I noticed that FS is for some reason stripping off (apparently..) the
SDP part from the INVITE.

Why do I believe that? Well, I used tcpdump on the FS box to capture the
network traffic and see what arrives actually. The INVITE received by
the network stack shows the full INVITE message including the SDP part.

On the other hand, when I make a call / INVITE from a phone which is
directly registered at FS, the INVITE message shown in the sip trace
includes the SDP.

Thus, I believe that FS has an issue parsing that particular INVITE
message properly.

Note: the same proxy, the same set-up works all sorts of other PBXs and
Soft-Switches (Asterisk, Avaya, 3com, Nortel, Cisco, Sonus, ...). It's
all tested.

Of course I can provide the FS SIP trace log and the corresponding
tcpdump. If any developer could have a quick look, I'd really appreciate
this.

Thanks and best regards,

Ingmar