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Sip signaling basics

Details

Below will offer you insight into the basics of SIP signaling.

Definition

SIP is establishing sessions between two or more telecommunications devices over the Internet.

 

SIP Headers:

  • INVITE :Invites a user to a call
     
  • ACK : Acknowledgement is used to facilitate reliable message exchange for INVITEs.
     
  • BYE :Terminates a connection between users
     
  • CANCEL :Terminates a request, or search, for a user. It is used if a client sends an INVITE and then changes its decision to call the recipient.
     
  • OPTIONS :Solicits information about a server's capabilities.
     
  • REGISTER :Registers a user's current location
     
  • INFO :Used for mid-session signaling

 

SIPsignaling.gif

SIP Errors:

  • 1xx: Provisional -- request received, continuing to process the request;
  • 2xx: Success -- the action was successfully received, understood, and accepted;
  • 3xx: Redirection -- further action needs to be taken in order to complete the request;
  • 4xx: Client Error -- the request contains bad syntax or cannot be fulfilled at this server;
  • 5xx: Server Error -- the server failed to fulfill an apparently valid request;
  • 6xx: Global Failure -- the request cannot be fulfilled at any server.
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