One of our clients has a Draytek Vigor 2920- their natted Snom phones behind it are registered to an Asterisk 1.4 server on an external public IP.<br><br>I've set QOS, bandwidth management and turned off the SIP ALG via telnet but I'm still having some problems with some of the phones losing registration if Asterisk is restarted.<br>
<br>I can see the phones sending SIP REGISTER messages, but they never arrive at the server; this happens in about half of the phones- with no consistency as to which lose registration.<br><br>It looks like the router is swallowing the messages, or there's some kind of NAT problem. Other clients at other sites are fine.<br>
<br>The problem clears if the phone is rebooted (renegotiates a new nat path?)<br><br>Any help warmly appreciated.<br><br>John<br>