FreeSWITCHers, As some of you may have noticed I frequently comment on SIP-related FreeSWITCH posts. Long story short I decided to finally put some of these thoughts and experiences down in writing. What I ended up with is a 21 page (and counting) document describing various SIP header fields, SDP information, RTP issues, DTMF issues, NAT traversal technologies, interop headaches, etc. I wrote a little intro and linked to the document if any of you would like to check it out (link at the end of post): http://blog.krisk.org/2012/06/everything-you-wish-you-didnt-need-to.html Of course I'd appreciate any feedback you may have. What do you disagree with? Find a typo? Have burning SIP/RTP/SDP/T.38/codec questions you'd like to see me address? Should I get into more implementation (FreeSWITCH) specific issues? Let me know. Thanks! -- Kristian Kielhofner