Question

We need to developed SIP Client, and have one basic doubt,

we got SIP UserId , password and server detail and would like to know few things,

1. What is difference between SIP Registration & SIP Log in , I believe, there is no something like SIP Login, its Custom SIP Request , and UserId / password will be used durring time of regiestration ,
   Please correct me, if I am wrong
2. We got to know the Audio Call flow, but all tutorial doesn’t say about voice server, assuming one party is calling and another party is accepted the call, then Media Session will get established, and i believe, both the party will receive one Server & Port no, from where both the parties will need to transfer and receive the voice packets.

Please correct me if I am wrong…

Answer 1

1. SIP defines the REGISTER method so that a user agent can associate a current Contact address with an address of record. See Section 10 of RFC 3261. There is no login method defined in RFC3261. However, any initial request can be challenged with a 401/407 response that requires the UAC to resend the initial request with authentication credentials. See Section 22.2 of RFC 3261.

2. Each party provides the other party with the IP address and port number(s) for media streams in the SDP (Session Description Protocol), delivered as the body of the SIP message with MIME type "application/sdp". Use of SDP within SIP is documented in the relevant sections of RFC 3261, and a tutorial can be found here.

There is a very fine SIP tutorial available here.