The client does not have STUN support. (I am not sure; because there is
no field to enter stun server address. However it may have an internal
STUN)
Actually the client is the "internet calling" feature of new Windows
Mobile 6.0.
I
am also nearly sure that there is no ALG in front of the UA. Plus, I am using
5061 on the SIP server as UDP port. So most of the ALG mechanisms do not mess
with my sip messages.
I
believe this is a misconfiguration issue. But I don't know how to troubleshoot
it.
Any help on the nat configuration would be wonderful.
Thanks,
ilker
Most likely the invite is not detected as NATed by your config and
force_rport and fix_nated_contact (which will solve your problem) are not
called.
If you use stun, it behaves badly. If not, you have an ALG in front
of the UA.
g-)
------- Original message -------
From: İlker Aktuna
(Koç.net) <ilkera@koc.net>
Sent: 9.4.'07, 9:32
>
Hi,
>
> I have a working configuration on my SER server. Most of
the users can make calls (both way incoming and outgoing) with no
problem.
> However, I have some clients that can't make calls.
>
When I analyze these by ngrep and/or tcpdump, I see that the SER server does not
reply the packet on the correct port.
>
> For example, I have a
testing client which is behind NAT.
> The client sends INVITE message from
UDP port 3023 to port 5061 of my SER.
> (cseq number is 1)
> SER
exchanges the message with the uplink sip gateway and when it receives a "OK"
response it forwards this message to the client's NAT IP address BUT on a
different port (14640) with correct cseq number (1)
>
> Of course,
this new port is not open on the NAT router and it does not reach the
client.
>
> I see that the first INVITE message has Contact field
with internal IP address of the client and the port number as 14640.
> So
the SER server sends the returning message to the external IP address with
internal port number.
>
> How can I fix this issue ?
>
> I can send the configuration of my SER server if that would help to
find the problem.