Hello, Great system, still setting it up for the first time. Thanks for everyone's work!! I have an internal extension setup that callers can press 0 to transfer to a cell phone (urgent calls) or leave a message in the voice mailbox. Everything works fine for the transfer, but after 3CX transfers the callers, they cannot hear the person on the cell phone. Cell phone user can hear the caller, but cannot respond. Probably a port issue on the Linksys firewall. I have to following ports forwarded to the 3CX server on the firewall; 9000 - 9015 TCP/UDP External calls 5060 - 5060 TCP/UDP SIP for external ext. future use. 1000 - 2000 TCP/UDP (tried with and without) RTP 3478 - 3478 TCP/UDP Stun Am I missing any ports that may be affecting these calls? Is there something else I am not thinking of? If I change the cell phone to a callcentric sip account on a soft phone it seems to work, however that softphone sits on a computer on the network - not really hitting the firewall. Any suggestions would be greatly appreciated! Thanks.