[Serusers] OptiPoint420 behind a NAT device

[hiSIPatH]

Hi all,

i have a ser setup (CentOS 4.4/ser 0.9.6) with several ip phones
(SNOM320 and Xlite30) and every thing seems to work fine. The ser
server has a public ip address 89.xxx.xxx.xxx and the ua are behind a
NAT device (corporate FW).

I want now to add some OptiPoint420 SIP but was unable to get them
working. That means that the registration is ok and calls to the
Optipoints from other ua (xlite or Snom) work but i was unable to
place a call from Optipoint to other ua.

In the trace you can notice that the INVITE is sent to ser with Src
Port 38625 and Dst Port 5060. But the response from ser is sent to Src
Port: 5060 (5060), Dst Port: 5060 (5060). The result is of couse ICMP
Destination unreachable (Port unreachable).

I have rtp proxy and ser running on the same server and my ser.cfg
looks like the one from the SER GettingStarted
http://siprouter.onsip.org/doc/gettingstarted/ch08s02.html). I read
the doc about "handling of NAT using RTP Proxy" but was unable to
change the config to get this scenario with OptiPoint working. Has
anyone managed to get OptiPoint to work with ser?

thx in advance?

No.     Time        Source                Destination           Protocol Info
     14 8.907171    89.xxx.xxx.xxx         89.xxx.xxx.xxx
SIP/SDP  Request: INVITE
sip:8001 at registrar.mydomaine.com;transport=udp, with session
description

Frame 14 (972 bytes on wire, 972 bytes captured)
Ethernet II, Src: AminoCom_02:02:02 (00:02:02:02:02:02), Dst:
AcerTech_9c:00:8d (00:00:e2:9c:00:8d)
Internet Protocol, Src: 89.xxx.xxx.xxx (89.xxx.xxx.xxx), Dst:
89.xxx.xxx.xxx (89.xxx.xxx.xxx)
User Datagram Protocol, Src Port: 38625 (38625), Dst Port: 5060 (5060)
Session Initiation Protocol

No.     Time        Source                Destination           Protocol Info
     15 8.907394    89.xxx.xxx.xxx        89.xxx.xxx.xxx         SIP
   Status: 407 Proxy Authentication Required

Frame 15 (772 bytes on wire, 772 bytes captured)
Ethernet II, Src: AcerTech_9c:00:8d (00:00:e2:9c:00:8d), Dst:
AminoCom_02:02:02 (00:02:02:02:02:02)
Internet Protocol, Src: 89.xxx.xxx.xxx (89.xxx.xxx.xxx), Dst:
89.xxx.xxx.xxx (89.xxx.xxx.xxx)
User Datagram Protocol, Src Port: 5060 (5060), Dst Port: 5060 (5060)
Session Initiation Protocol