Kamailio as a front-end proxy - sr-users

1 Mar 2016

Hello everybody,

I am a new user of Kamailio (4.3.1), I am working with it since 1-2 months.
The thing that I'm trying to do is to build the following system:

same LAN

192.168.0.1
Alice
proprietary SIP Server
                         [Public_IP_X]   ------------ [Public_IP_Y]
Kamailio [172.26.0.1] ---------- [172.26.0.1]  with
192.168.0.1
registrar
Bob

Obviously Kamailio has to translate the local addresses of Alice and Bob,
e.g. to use the Nathelper module.
The module is doing well its job because the Contact headers are replaced
with the Public_IP_X when a REGISTER message is sent by Alice's or Bob's
sip phones (I am using Linphone and Zoiper as clients).
Once the incoming sip register was treated by Kamailio it is sent to the
proprietary SIP Server. The server sends 200 OK to Kamailio and the proxy
relays the message to the clients. So the sip registration for me it is OK.

But when it comes to initiate a call from Alice to Bob the things are not
as I expect it. The initial request INVITE sent from Alice goes to the sip
server but then the server instead of sending the INVITE for Bob through
Kamailio, it sends the message directly to Bob's device.
Does anyone knows how to "tell" to the sip server, using the SIP protocol,
that it must use the proxy?
The only thing I have in mind is to force Kamailio to replace the contact
of Alice and more precisely the host/ip address by the proxy's host/ip
address.
I tested this idea and the sip server did what I was expecting but for me
this is not a proper solution.
To do that I used this discussion -
http://opensips.org/pipermail/users/2010-October/014873.html
Thank you in advance for your attention !

Best regards,

Anton