[Serusers] SIP Contact header field issue incase of NAT - sr-users

1 Sep 2006

Hi All,

  I have problem connecting Nokia Phone with SER. The problem is When SER receives the
registration request from the Nokia phone. The registration request contain the
phone's private IP (192.xxx.xx.xx), since we use wifi for connection. Our proxy
detects that since this is a private IP handles the NAT translation and determines the
phone public IP address (e.g., 202.xxx.xx.xx, port xx). Our SIP proxy informs the phone
that registration is successful but the contact information is changed from
userid(a)192.xxx.xxx.xx to userid(a)202.xxx.xxx.xx, port xx.  On recieving this changed
contact info the Phone rejects 200 Ok.

     We tried to contact nokia people and they said that its part of RFC3261 to reject
such contacts. After this I have also gone through RFC 3261 section "10.2.4" and
it seems that phone is doing rite.  Can any body tell me why SER is changing the contact
address in case of NAT. It would be higly appreciated if you can give me some reference
from some RFC or other document which I can show to nokia people.

Best Regards,
Abdul Qadir

---------------------------------
How low will we go? Check out Yahoo! Messengers low  PC-to-Phone call rates.