On asterisk remote doesn't work voice

Hi all,
inside my lan there is an asterisk server for voip calls.
Inside my lan i can call other users and speek with them. Outside my lan i can call others user, connection is established but i don’t hear voice.
Inside my sip.conf theresn’t any notification for “canreinvite”, i tried to change for user (on asterisk) settings with canreinvite = yes but doesn’t work yet.
Ideas?!?

Ciao,
stefano

Try to post your configuration here.