SIP Request Line
Request-Line = Method SP Request-URI SP SIP-Version CRLF
Method:
1. REGISTER for registering contact information.
2. INVITE, ACK, and CANCEL for setting up sessions.
3. BYE for terminating sessions.
4. OPTIONS for querying servers about their capabilities.
Request-URI:
SIP-Version:
1. HTTP <----> SIP
2. HTTP1.1 <----> SIP/2.0
SIP Response Line
Status-Line = SIP-Version SP Status-Code SP Reason-Phrase CRLF
Status-Code:
1xx: Provisional -- request received, continuing to process the request;
100 Trying
180 Ringing
181 Call Is Being Forwarded
182 Queued
183 Session Progress
2xx: Success -- the action was successfully received, understood,and accepted;
200 OK
3xx: Redirection -- further action needs to be taken in order to complete the request;
300 Multiple Choices
301 Moved Permanently
302 Moved Temporarily
305 Use Proxy
380 Alternative Service
4xx: Client Error -- the request contains bad syntax or cannot be fulfilled at this server;
400 Bad Request
401 Unauthorized
402 Payment Required
403 Forbidden
404 Not Found
405 Method Not Allowed
406 Not Acceptable
407 Proxy Authentication Required
408 Request Timeout
410 Gone
413 Request Entity Too Large
414 Request-URI Too Long
415 Unsupported Media Type
416 Unsupported URI Scheme
420 Bad Extension
421 Extension Required
423 Interval Too Brief
480 Temporarily Unavailable
481 Call/Transaction Does Not Exist
482 Loop Detected
483 Too Many Hops
484 Address Incomplete
485 Ambiguous
486 Busy Here
487 Request Terminated
488 Not Acceptable Here
491 Request Pending
493 Undecipherable
5xx: Server Error -- the server failed to fulfill an apparently valid request;
500 Server Internal Error
501 Not Implemented
502 Bad Gateway
503 Service Unavailable
504 Server Time-out
505 Version Not Supported
513 Message Too Large
6xx: Global Failure -- the request cannot be fulfilled at any server.
600 Busy Everywhere
603 Decline
604 Does Not Exist Anywhere
606 Not Acceptable
SIP Header Fileds
TO
To: Carol <sip:carol@chicago.com>
From
From: "Bob" <sips:bob@biloxi.com> ;tag=a48s
From: sip:+12125551212@phone2net.com;tag=887s
From: Anonymous <sip:c8oqz84zk7z@privacy.org>;tag=hyh8
Call-ID
Call-ID: f81d4fae-7dec-11d0-a765-00a0c91e6bf6@foo.bar.com
CSeq
CSeq: 4711 INVITE
Max-Forwards
Via
Branch ID: MUST always begin with the characters "z9hG4bK"
Contact
SIP Methods
REGISTER
UA <----> Proxy <----> Location Service
OPTIONS
DIALOG
only 2xx and 101-199 responses with a To tag, where the request was INVITE, will establish a dialog.
A dialog established by a non-final response to a request is in the "early" state and it is called an early dialog.
CANCEL
Others
only INVIET has ACK.
"an ACK for a non-2xx response will also have the same branch ID as the INVITE whose response it acknowledges", that means ACK with non-success response will be part of the INVITE transaction.
It only has a separate branch ID for 2xx success response which then belongs to another transaction.
Home-Based Routing (S8HR)
