I have configured the SIP trunk [unauthenticated] to my services provider for outbound calling. I can make a call using the SIP trunk configured in callmanager, but call is getting disconnect after every 15 min. Our service provider says every 15 min...

Hi,I am having CM5.1 and configured SIP trunk (unauthenticated) directly to my services provider. Also i have 2851 router in which NAT is configured with the services provider IPs for call manager and phones.I can able to make calls using this SIP tr...