FYI: Asterisk puts URIs in messages which violates the SIP spec and can't be accepted by URI parsers: username includes a whitespace. See for example the From header field. Attached is example of an incorrect message and related parts of RFC3261 specification. (Who doesn't want to dig into parser details may want to realize that whitespaces are used as uri delimitors in first request line and can't thus be a uri part.) I would recommend that the stack generally validates URIs for such glitches and uses other word for "no callId". "anonymous" is in frequent use by other software. -jiri OPTIONS sip:195.37.77.101 SIP/2.0 Via: SIP/2.0/UDP 24.172.18.166:5060;branch=z9hG4bK03be4cf3 From: "No CallID" <sip:No CallID@24.172.18.166>;tag=as2746f4f3 To: <sip:195.37.77.101> Contact: <sip:No CallID@24.172.18.166> Call-ID: 72b6aaf63319c64e4a96a6cd42245f7e@24.172.18.166 CSeq: 102 OPTIONS User-Agent: Asterisk PBX Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER Content-Length: 0 3261: From->name_addr|addr_spec addr_spec->SIP_URI SIP_URI->userinfo user_info->user user->1*( unreserved / escaped / user-unreserved user-unreserved = "&" / "=" / "+" / "$" / "," / ";" / "?" / "/" unreserved = alphanum / mark mark = "-" / "_" / "." / "!" / "~" / "*" / "'" / "(" / ")" -- Jiri Kuthan http://iptel.org/~jiri/ iptel.org -- creaters of the fastest SIP server