SIP Connection
 

Hello everyone, I have SIP setup on the N900 and everything is working ok but after like 30 minutes, the phone does not ring. It says its online and I have to sign out and sign in again for the calls to come in. This acct is used only for incoming calls so I don't outgoing calls.
Does anyone know what is the problem?

Below is my Setup:
Google # is going to IPKall acct which is connected to a free pbxes.org account.

N900 menu:Edit account for SIP
Address: username@pbxes.org
Password: thepassword
Enable: Check

Advanced settings:
Use for telephone numbers: Uncheck
Username: pbxes.org username
Transport: UDP, this was in Auto but was told to change it to UDP
Outbound proxy: pbxes.org
Port: 5060
Discover public address: Check
Loose routing: Uncheck
Keep-alive mechanism: Auto
Keep-alive period: Auto
Auto-detect STUN: Check