Hi, FreeSWITCH (Version 1.2.7 git 93e2a38) throws this error in the CLI when a REGISTER without CONTACT-header hits it. FS responds with 500 Internal Server Error The requesting side is sending a second REGISTER with Contact then and it registeres. Some "AVM FritzBox" hardware-boxes send such a REGISTER. Here a (cleaned) SIP-Trace ------------------------------------------------------------------------ recv 620 bytes from udp/[1.2.3.4]:5060 at 11:01:06.214597: ------------------------------------------------------------------------ REGISTER sip:sipproxy.somebusiness.com SIP/2.0 Via: SIP/2.0/UDP 1.2.3.4:5060;rport;branch=z9hG4bK4F974DA26FBE794A From: <sip:user.user2@sipproxy.somebusiness.com>;tag=3665871555 To: <sip:user.user2@sipproxy.somebusiness.com> Call-ID: 9BB803703627C9DF@1.2.3.4 CSeq: 2078 REGISTER Max-Forwards: 70 User-Agent: AVM FRITZ!Box Fon WLAN 7390 84.05.50 (Dec 11 2012) Supported: 100rel,replaces Allow-Events: telephone-event,refer,reg Allow: INVITE,ACK,OPTIONS,CANCEL,BYE,UPDATE,PRACK,INFO,SUBSCRIBE,NOTIFY,REFER,MESSAGE,PUBLISH Accept: application/sdp, multipart/mixed Accept-Encoding: identity Content-Length: 0 ------------------------------------------------------------------------ 2013-03-21 12:01:06.214194 [ERR] sofia_reg.c:1914 NO CONTACT! ip: 1.2.3.4, port: 5060 send 322 bytes to udp/[1.2.3.4]:5060 at 11:01:06.214998: ------------------------------------------------------------------------ SIP/2.0 500 Internal Server Error Via: SIP/2.0/UDP 1.2.3.4:5060;rport=5060;branch=z9hG4bK4F974DA26FBE794A From: <sip:user.user2@sipproxy.somebusiness.com>;tag=3665871555 To: <sip:user.user2@sipproxy.somebusiness.com>;tag=cFDNr9NQa5g9m Call-ID: 9BB803703627C9DF@1.2.3.4 CSeq: 2078 REGISTER Content-Length: 0 ------------------------------------------------------------------------ recv 715 bytes from udp/[1.2.3.4]:5060 at 11:01:06.252877: ------------------------------------------------------------------------ REGISTER sip:sipproxy.somebusiness.com SIP/2.0 Via: SIP/2.0/UDP 1.2.3.4:5060;rport;branch=z9hG4bK394B9487FAFBC468 From: <sip:user.user2@sipproxy.somebusiness.com>;tag=3665871555 To: <sip:user.user2@sipproxy.somebusiness.com> Call-ID: 9BB803703627C9DF@1.2.3.4 CSeq: 2079 REGISTER Contact: <sip:user.user2@1.2.3.4;uniq=77F5786DCDB3B0B3999878F7FB4C0> Max-Forwards: 70 Expires: 1800 User-Agent: AVM FRITZ!Box Fon WLAN 7390 84.05.50 (Dec 11 2012) Supported: 100rel,replaces Allow-Events: telephone-event,refer,reg Allow: INVITE,ACK,OPTIONS,CANCEL,BYE,UPDATE,PRACK,INFO,SUBSCRIBE,NOTIFY,REFER,MESSAGE,PUBLISH Accept: application/sdp, multipart/mixed Accept-Encoding: identity Content-Length: 0 ------------------------------------------------------------------------ send 595 bytes to udp/[1.2.3.4]:5060 at 11:01:06.265145: ------------------------------------------------------------------------ SIP/2.0 200 OK Via: SIP/2.0/UDP 1.2.3.4:5060;rport=5060;branch=z9hG4bK394B9487FAFBC468 From: <sip:user.user2@sipproxy.somebusiness.com>;tag=3665871555 To: <sip:user.user2@sipproxy.somebusiness.com>;tag=Dr6Dt46t7D7Ug Call-ID: 9BB803703627C9DF@1.2.3.4 CSeq: 2079 REGISTER Contact: <sip:user.user2@1.2.3.4;uniq=77F5786DCDB3B0B3999878F7FB4C0>;expires=1800 Date: Thu, 21 Mar 2013 11:01:06 GMT User-Agent: SIP-SERVER Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY Supported: timer, precondition, path, replaces Content-Length: 0