Sip signaling basics

Details

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

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

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.