SIP Question: The Grandstream GXP2000 126.96.36.199 sends SIP REGISTER requests with a To tag. Is my proxy wrong in refusing the request?
REGISTER sip:server SIP/2.0 Via: SIP/2.0/UDP 188.8.131.52:5074;branch=z9hG4bK0b90873d634698eb From: "phone 123" <sip:123@server>;tag=c29eb9104c6a5a86 To: <sip:123@server>;tag=as77984b6 Contact: <sip:email@example.com:5074;transport=udp> Supported: path Authorization: Digest username="123", realm="server", algorithm=MD5, uri="sip:server", nonce="0997652c", response="3b91afb768c11ae0a0405e1bed41bc23" Call-ID: firstname.lastname@example.org CSeq: 56349 REGISTER Expires: 3600 User-Agent: Grandstream GXP2000 184.108.40.206 Max-Forwards: 70 Allow: INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE,UPDATE,PRACK,MESSAGE Content-Length: 0
Answer: no, the proxy is right. RFC 3261 says this about it.
220.127.116.11 To A request outside of a dialog MUST NOT contain a To tag; the tag in the To field of a request identifies the peer of the dialog. Since no dialog is established, no tag is present. 10.2 Constructing the REGISTER Request A REGISTER request does not establish a dialog.
Grandstream has already fixed this bug long ago (in version 18.104.22.168, beginning of 2007) as you can see in the release notes on www.grandstreamsucks.com. You should upgrade the firmware.