[SR-Users] dropped calls after 38 seconds openSER

Greetings list, I am experiencing a strange behavior with openser 1.3.2 running on ubuntu 10. I have a basic configuration (see bellow) and i am using Linphone for iPad as my client. I have 2 users registered and I am able to place calls no problem. The problem is that the calls (audio or A/V) drop after 38 seconds exactly, this behavior is pretty consistent, 38 seconds is all I can get. There is no firewall in front of the clients. Here is my configuration, ip addresses changed to protect the innocent: http://pastie.org/private/x1ck8rxjcxv6hl44hrmqg You can see the logs of the call here (the majority): http://pastie.org/private/4fj5efpbsrxan8plzqvfza Am I missing something or is there anything that needs to be changed in the routing/configuration to achieve basic functionality? Thank you in advance!