Schematic diagram of the basic registration process:
The registration process is described as follows:
1. The SIP proxy sends a REGISTER request to the SIP server;
2. The SIP server sends a response 401 to the SIP proxy, and provides the authentication system and parameters suitable for the SIP proxy in the WWW-Authenticate field of the response message header;
3. The SIP proxy re-sends a REGISTER request to the SIP server, and gives a letter of trust in the Authorization field of the request, including authentication information;
4. The SIP server verifies the request. If it checks that the SIP proxy identity is valid, it sends a successful response 200 OK to the SIP proxy. If the identity is invalid, it sends a denial of service response.
Example of registration signaling message:
Register sip: SIP server code@destination domain name or IP address port SIP/2.0
Via:SIP/2.0/UDP source domain name or IP address port
From:<sip:SIP device code@source domain name>;tag=185328220
To: <sip:SIP device code@source domain name>
Call-ID:[email protected]
CSeq:1 Register
Contact: <sip:SIP device code@source IP address port>
Max-Forwords:70
Expires: 7200
Content-Length: 0
SIP/2.0 401 Unauthorized
To: sip:SIP device code@source domain name
Content-Length: 0
CSeq:1 Register
Call-ID:[email protected]
From:<sip:SIP device code@source domain name>;tag=185328220
Via:SIP/2.0/UDP source domain name or IP address port
WWW-Authenticate: Digest realm=”64010000”,nonce=”6fe9ba44a76be22a”
Register sip: SIP server code@destination domain name or IP address port SIP/2.0
Via:SIP/2.0/UDP source domain name or IP address port
From:<sip:SIP device code@source domain name>;tag=185328220
To: <sip:SIP device code@source domain name>
Call-ID:[email protected]
CSeq:2 Register
Contact: <sip:SIP device code@source IP address port>
Authorization: Digest username=”64010000002020000001”,realm=”64010000”, nonce=”6fe9ba44a76be22a”,uri=”sip:[email protected]:5060”,response=”9625d92d1bddea7a911926e0db054968”,algorithm=”MD5”
Max-Forwords:70
Expires: 7200
Content-Length: 0
SIP/2.0 200 OK
To: <sip:SIP device code@source domain name>;tag=69113a2a
Contact: sip:SIP device code@source IP address port
Content-Length: 0
CSeq:2 Register
Call-ID:[email protected]
From:<sip:SIP device code@source domain name>;tag=185328220
Via:SIP/2.0/UDP source domain name or IP address port
Date:2010-11-02T15:01:26.115
Expires: 7200