SIP Over internet

Hi,

I’ve an Asterisk setup in my LAN and run perfectly fine with all my SIP phones in the same LAN. The problems come when I use my Xten-Lite from different subnet (eg broadband from open internet), where most of the time the calls didn’t hang up properly (I hv my nat=yes). Somehow the SIP end packet is not reach my Asterisk.

Any suggestions?

thnks
CS