[Freeswitch-users] Got more 404s than should.

Hi, Please help me take a look into this: http://pastebin.freeswitch.org/8816 My problem is why the first one keep sending 404s even got the ACK? It seems that in the first test the ACK is not recognized by FS so it keep sending 404. The only difference I can see of the two ACK-404 is the first one missing a tag of TO, is that related? Shouldn't the tag optional? PS: it works OK if I dial an exists number and get answered. It only happens on unanswered messages like 404 or 503 etc. Thank you.