I am trying to diagnose problem with external extension and wondering if there is a way to trace packets that the router sends to the internet. The external extenstion is a Thomson 780WL ADSL router with built in VOIP so there is no firewall or STUN stuff to configure. When external extension makes a call I use wireshark on the 3cx server host to see what happens: receive INVITE from external extension reply with status 407 -proxy auth required receive ACK receive INVITE with Cseq 2 and proxy authorisation stuff send status 100 trying, 180 ringing send status 200 OK with session descriptor then 3cx repeatedly sends the status 200OK until after 30 sec it disconnects the call with a BYE and a note that no ACK was received. If I look on the external extension router system log I see VOIP send INVITE VOIP recv 407 proxy auth required VOIP send ACK VOIP Send INVITE VOIP recv 100 VOIP recv 180 Voip recv 200 OK VOIP send ACK So the extension is telling me it sent an ACK, but it does not arrive at 3cx. The audio is working fine in both directions until the call is cut by 3cx because it didn't receive the final ACK. What is puzzling me is that the first ACK is received no problem. So what I want to do is analyse the packets coming out of the external extension to see what desintaion is used on the final ACK - but I can't use wireshark as this is all internal to the router. The router has telnet interface and various commands like ip debug traceconfig plus snmp - is there a way to make it foward its packets to the LAN or dump them to a log file or something like that ? Alterhativel anyone have an idea why the first ACK makes it OK, but the second ACK gets lost ?