I have a system running CVS HEAD 6/30/2004. We've only been using it for PSTN to channel bank handsets, but have decided to add sip phones into the mix. Now I have quite a few systems running sip phones just fine as well as some running both sip and analog via channel banks or tdm cards. When we tried to set up some sip extensions (they are behind nats, we are using xten light, and have canreinvite=no as well as nat=yes set in the sip.conf), we only get one way audio. You can hear the other end (be it the asterisk voice prompts or another non-sip user), but the other user cannot hear the sip phone user talking. It gets even more complex. If using the sip phone to call voicemail, or any other asterisk based services the sip user can get dtmf through (yes rfc2833). The asterisk box is on a public IP address, no firewall or nat. The sip clients are 'generally' behind a nat (we've tested from several locations including my home, which I have multiple sip UA's behind a nat, and the very same xten lite is able to work just fine with any of my local asterisk systems (or any others I've tested - all outside of my home nat). The calls are being made with ulaw as the only codec allowed. The sip debug indicates that the call setup has worked and agreed upon ulaw as the codec. CLI provides multiple repeats of the following two errors: rtp.c:1215 ast_rtp_write: Not sure about sending format SLINR packets rtp.c:1058 ast_rtp_raw_write: Not sure about timestamp format for codec Any thoughts, comments, suggestions? Google has been less than helpful given any keywords I came up with to avoice all the NAT/Firewall one way audio posts. -Chris