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A REGISTER request may contain a message body, although its use is not defined in the standard Depending on the use of the Contact and Expires headers in the REGISTER request, the registrar server will take different action. If no expires parameter or Expires header is present, a SIP URI will expire in 1 hour. The presence of an Expires header sets the expiration of Contacts with no expires parameter. If an expires parameter is present, it sets the expiration time for that Contact only. Non-SIP URIs have no default expiration time. The CSeq is incremented for a REGISTER request.
Posted by HamidAliKhan
The REGISTER method is used by a user agent to notify a SIP network of its current Contact URI (IP address) and the URI that should have requests routed to this Contact. SIP registration bears some similarity to cell phone registration on initialization. A REGISTER request may contain a message body, although its use is not defined in the standard Depending on the use of the Contact and Expires headers in the REGISTER request, the registrar server will take different action. If no expires parameter or Expires header is present, a SIP URI will expire in 1 hour. The presence of an Expires header sets the expiration of Contacts with no expires parameter. If an expires parameter is present, it sets the expiration time for that Contact only. Non-SIP URIs have no default expiration time. The CSeq is incremented for a REGISTER request. The use of the Request-URI, To, From, and Call-ID headers in a REGISTER request is slightly different than for other requests.
Posted by dave
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