I made some progress today by using UDP (silly me):
but I still have a problem. Is there a way to bypass this? Some phone setting that I missed?
Below is the telephone trace:
Received from udp:192.168.1.44:2057 at 20/5/2008 19:52:49:680 (453 bytes):
NOTIFY sip:251@192.168.1.43:2057;line=m00xv4ly SIP/2.0
Via: SIP/2.0/UDP 192.168.1.44:2057;branch=z9hG4bK5e3acadf;rport
To: <sip:251@192.168.1.43:2057;line=m00xv4ly>
From: ;tag=4442
Date: Tuesday, May 20, 2008 5/20/2008 7:52:49 PM
Call-Id: 3c268afd0ea6-tk5ueq9zigfb@snom360-000413230077
CSeq: 102 NOTIFY
Event: message-summary
Content-Type: application/simple-message-summary
Content-Length: 45
Messages-Waiting: yes
Voicemail: 1/1 (1/1)
--------------------------------------------------------------------------------
Sent to udp:192.168.1.44:2057 at 20/5/2008 19:52:49:690 (424 bytes):
SIP/2.0 403 Use Proxy
Via: SIP/2.0/UDP 192.168.1.44:2057;branch=z9hG4bK5e3acadf;rport=2057
From: <;tag=4442>
To: <sip:251@192.168.1.43:2057;line=m00xv4ly>
Call-ID: 3c268afd0ea6-tk5ueq9zigfb@snom360-000413230077
CSeq: 102 NOTIFY
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO
Allow-Events: talk, hold, refer
Supported: timer, 100rel, replaces, callerid
Content-Length: 0