[Freeswitch-users] Sip phone lose communication appears registered

Hello, Just setup an FS test server on amazon ec2. Everything works flawlessly but after a while sip phone arent reacheable even as they seem registered on FS and are able to do outbound calling. Any idea of what could be happening? If i restart the sip phones every starts working again for a litrle while. Thanks, Sent from my iPhone