Dialogic 6.2 Manuale Utente

Understanding the SIP Protocol

November 2009

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You can use the Session Initiation Protocol (SIP), an 

application-layer control (signaling) protocol, to create, modify, and 

terminate sessions with one or more participants. 

These sessions include internet telephone calls, multimedia 

distribution, and multimedia conferences. SIP invitations used to 

create sessions carry session descriptions that allow participants to 

agree on a set of compatible media types. SIP makes use of elements 

called proxy servers to help do the following:

„

Route requests to the user's current location 

„

Authenticate and authorize users for services

„

Implement provider call-routing policies

„

Provide features to users. 
SIP also provides a registration function that allows users to 

upload their current locations for use by proxy servers. 

SIP runs on top of several different transport protocols. 

This section has the following sections:

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„

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There are many applications of the internet that require the creation 

and management of a session (a session is considered to be an 

exchange of data between an association of participants). The 

implementation of these applications is complicated by the practices 

of participants: users might move between endpoints, they might be 

addressable by multiple names, and they might communicate in 

several different media - sometimes simultaneously. (For copyright 

information on this section, see 

.)