We have had ongoing issues with trying to get remote extensions working. We recently upgraded our router to a Cisco Small Business Pro so that we could guarantee ports correctly configured. I have now set up 3 remote extensions using the 3CX VOIP phone to avoid any hardware issues. I can get all three working "in the office" both with and without the 3CX tunnel. On remote sites I can get all 3 working WITH the 3CX Tunnel, but none working without it. This is 3 different laptops at 3 different remote sites with 3 different ISP's and 3 different routers. I don't want to use 3CX tunnel as my eventual aim is to use 3CX iPhone and Android apps. I have tried the iPhone app and it works in the office but not at remore locations. I have used the firewall checker on the 3CX phone system and everything passes, I have disabled (temporarily) the Cisco Router firewall to eliminate firewall issues. I have ports 5060, 5080, 5090 and 9000-9049 forwarded on the Cisco router to the PBX device. The debug window on the 3CX VoipPhone, just says Sending STUN request Connection to Server failed. What else can I check, or how can I trace the issue further? Gary.