Registering to Asterisk Behind Cisco Routers

Tonight a buddy and myself were playing with Asterisk. In order for him to be able to register to my server from outside my network we had to make some changes to my router. I am behind a Cisco 2650 Router, and we had to disable this in IOS:

no ip nat service sip udp port 5060

Note, that once this is disabled, you will no longer be able to register out to other Asterisk Servers until you re-enable it with.

ip nat service sip udp port 5060