Hi,

I'm behind a router with (symetrical) NAT. The register session seems to work fine. But the Invite message is only send to the SIP server, the SIP server doesn't forward the message. I use one of the latest ATLSIP versions (atlsip_src-1.1.0.zip and OpenSBC-1.1.5_RC5-Final.tar.gz) with no local changes and the SIP server works fine with other clients.
I have check the Invite messages of ATLSIP compared with one from another Client, I didn't see anything uncommon. But I notice a difference in the register session.
In the first Register msg I will send a Via like this...

Via: SIP/2.0/UDP 192.168.1.33:5060;iid=5202;branch=z9hG4bK237d59b9890019109898c8718fdcc964;uas-addr=85.25.254.113;rport

Where 192.168.1.33:5060 is my local IP. I will get a 401 Unauthorized as expected with the following Via...

Via: SIP/2.0/UDP 192.168.1.33:5060;iid=5202;branch=z9hG4bK4725f9bb890019109898c8718fdcc964;uas-addr=85.25.254.113;rport=11879;received=94.222.208.44

The sip server adds the rport and received to signaling me my public IP and Port. The difference between ATLSIP and the other client is the Via of second Register msg.

ATLSIP:
Via: SIP/2.0/UDP 192.168.1.33:5060;iid=5202;branch=z9hG4bK733ff9bb890019109898c8718fdcc964;uas-addr=85.25.254.113;rport
other Client:
Via: SIP/2.0/UDP 94.222.208.44:11961;iid=4553;branch=z9hG4bK8b62e6bb890019108621f8da1538e6d2;uas-addr=85.25.254.113;rport

ATLSIP uses the same IP, Port combination as on the first Register while the other client replaces the IP and Port with those from the sip server (send in the Via from 401).

I guess the SIP server uses the IP, Port from the Via in the second Register message to forward other messages later, like the Invite which isn't forwarded from the sip server to the destination client.

Is this a bug in ATLSIP or did I have make mistake somewhere?

Thanks a lot.