Sip Messages - HP MSR SERIES Configuration Manual

Consistent communication method. Management becomes easier as the result of consistency in
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dialup mode and system access method used by branches, SOHOs, and traveling personnel.
Quick launch. The system can be updated quickly to accommodate new branches and personnel,
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and changes resulting from job rotation or relocation.
Easy to install and maintain. Nonprofessional individuals can install and maintain SIP systems.
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SIP messages

SIP messages, including SIP request messages and SIP response messages, are encoded in text mode.
SIP request messages include INVITE, ACK, OPTIONS, BYE, CANCEL, and REGISTER. RFC 3261 defines
the following six request messages:
• INVITE—Used to invite a user to join a call.
ACK—Used to acknowledge the response to a request.
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OPTIONS—Used to query for the capabilities.
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BYE—Used to release an established call.
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CANCEL—Used to give up a call attempt.
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• REGISTER—Used to register with the SIP registrar.
SIP response messages, used to respond to SIP requests, indicate the status of a call or registration,
succeeded or failed. Response messages are distinguished by status codes. Each status code is a 3-digit
integer, where the first digit defines the class of a response, and the last two digits describe the response
message in more detail.
Table 237 Status codes of response messages
Code
100–199
200–299
300–399
400–499
500–599
600–699
SIP fundamentals
Registration
In a complete SIP system, all SIP endpoints working as UAs should register with SIP registrars, providing
information such as location, session capabilities, and call policy.
Typically, a SIP UA sends its registrar a REGISTER request at startup or in response to an administratively
registration operation, carrying all the information that must be recorded. Upon receipt of the request, the
registrar sends back a response notifying receipt of the request, and a 200 OK (SUCCESS) message if
the registration is accepted. The following figure shows the message exchange.
Description
Request is received and is being processed.
Request is successfully received, understood, and accepted.
Further action needs to be taken to process the request.
Request contains bad syntax, and therefore cannot be processed.
Request cannot be processed due to UAS or server error.
Request cannot be processed by any UAS or server.
630
Class
Provisional
Success
Redirection
Client error
Server error
Global error