Cisco 7911 NAT issue


After much testing and trying to work out whats the cause of my problem i’ve ended up here.

The problem in which i am having is :

8x Cisco 7911 all flashed with SIP firmware

They work fine locally on the same local network, when i use away from the office they do not want to connect.

I have two draytek routers linked to the two sites via lan to lan, i know this is working as i’ve got a cisco 7940G working fine.

Any ideas?


Cisco phones are intended for corporate networks, where you will have at least a VPN. At least the earlier ones don’t support NAT.