This chapter describes the main functions and components as well as response and request methods of the SIP.
SIP Background Information
This chapter describes the motivation that led to the development of SIP.
Functions of SIP
This chapter describes the abilities and disabilities of SIP.
Components of SIP
This chapter describes the terms Client
in context with SIP.
Request Methods of SIP
This chapter describes the purpose of request methods.
SIP Request Method – ACK
The request method ACK is used to acknowledge the reception of a final response to an INVITE request.
SIP Request Method – BYE
The request method BYE is used to end sessions.
SIP Request Method – CANCEL
The request method CANCEL is used to cancel pending transactions.
SIP Request Method – INVITE
The request method INVITE is used to indicate that a user or service wishes to participate in a session.
SIP Request Method – MESSAGE
This request method may be used to support instant messaging over SIP.
SIP Request Method – NOTIFY
This request method may be used to provide specific event notification. See also SUBSCRIBE method.
SIP Request Method – OPTIONS
The request method OPTIONS is used to query a server about its capabilities.
SIP Request Method – PRACK
This request method provides a provisional response used to establish a connection before call completion.
SIP Request Method – REFER
This request method provides the signaling for a user to transfer one user to another.
SIP Request Method – REGISTER
The request method REGISTER is used to inform a registrar server about its current location. It also contains information about when the registration is valid.
SIP Request Method – SUBSCRIBE
This request method may be used to request notification of specific events. See also NOTIFY method.
SIP Request Method – UPDATE
This request method provides the mechanism for a client to update parameters of a session (such as the set of media streams and their codecs), but has no impact on the state of a dialog.
INVITE Request Message Format of SIP
The INVITE request message format describes which content an INVITE request message must have.
Response Message Format of SIP
The INVITE response message format describes which content a response to an INVITE request message must have.
Response Types of SIP
This chapter describes which status codes exist and which functions they have.
SIP Informational Responses
The 1xx responses provide information concerning the INVITE messages.
SIP Success Responses
The 2xx responses provide information indicating that the request was successful and may give additional information.
SIP Redirect Responses
The 3xx responses give information about the user's new location, or about alternative services that might be able to satisfy the call.
SIP Client Error Responses
The 4xx responses are definite failure responses from a particular server.
SIP Server Error Responses
The 5xx responses are failure responses given when a server itself has erred.
SIP Global Failure Responses
The 6xx responses indicate that a server has definitive information about a particular user, not just the particular instance indicated in the request URI.
It is helpful to clarify the various terms used when discussing the SIP protocol:
Registration in SIP
This chapter describes the registration process in SIP.
SIP Session Example
This chapter describes an example of a typical SIP session.