Hi again! I decided, "just for fun", to install Asterisk on a server of mine (available in Internet) and to log on my mobile phone on this server. This Server communicate with my Asterisk at home and if I call a phone at home from my mobile phone (logged on the Asterisk on the second server), it work perfectly with a very good audio quality. If I log my mobile phone (and just tried with the PC of my father) direct on my Asterisk at home it does NOT work or the audio quality is very poor... So, I'm thinking I have somewhat misconfigured on my Gateway, but I just have that: /sbin/iptables -t nat -A PREROUTING -p udp --dport 5060 -j DNAT --to-destination 192.168.20.120:5060 What can be the problem? Thanks Luca Bertoncello (lucabert at lucabert.de)