SIPSESSION INITIATION

PROTOCOL

CSC 255

Sailee Choudhary

AGENDA

Introduction to SIP Network elements needed in SIP SIP Message types SIP Session establishment and termination SIP call redirection SIP call proxying

INTRODUCTION

SIP is the core protocol for initiating, managing and terminating sessions in the Internet

 It is an application layer protocol designed to be independent of the underlying transport layer.

SIP sessions involve one or more participants and can use unicast or multicast communication.

NETWORK ELEMENTS

User Agent: 1.User Agent Client (UAC)2.User Agent Server (UAS)

Proxy Server Registrar Redirect Server Session border controller Gateways

SIP MESSAGE TYPES

Requests – sent from client to server INVITE : Used to establish a media session

between user agents. ACK : Confirms reliable message exchanges. BYE : Terminates a session between two users

in a conference. CANCEL : Terminates a pending request. OPTIONS : Requests information about the

capabilities of a caller, without setting up a call. REGISTER : Used by a UAC to indicate its

current IP address and the URLs for which it would like to receive calls.

SIP MESSAGE TYPES

Responses – sent from server to the client Success: The action was successfully

received, understood, and accepted. Redirection :  Further action needs to be

taken to complete the request. Client Error: The request contains bad syntax

or cannot be fulfilled at the server. Server Error: The server failed to fulfill an

apparently valid request. Global failure : The request cannot be fulfilled

at any server.

REQUEST AND RESPONSE HEADER FOR ALL TYPES OF MESSAGES

SIP MESSAGE EXAMPLE

SIP SESSION ESTABLISHMENT AND CALL TERMINATION

SIP CALL REDIRECTION

CALL PROXYING

Thank you