Part 2
SIP at a Glance
In This Part
ᮣ Working with existing protocols
ᮣ Extending SIP to multimedia sessions
ᮣ Getting to know SIP presence
ᮣ Examining SIP components
ᮣ Following an example of basic operations
S
IP is an application layer Internet protocol for establishing,
manipulating, and tearing down communication ses-
sions. You can do a lot more with SIP than set up telephone
calls. The protocol is designed to be extensible — meaning
SIP can be easily extended to accommodate video, instant
messaging (IM), and yet-to-be-invented communications
media and features. (XML is an example of another extensible
language.) Aside from supporting communication call setup
and tear down, SIP also currently supports extensions for
instant messaging as well as advertising and tracking user
availability (both familiar today in Yahoo! and AOL Instant
Messenger).
SIP is used to identify, locate, and enjoin parties who wish to
communicate using any peer-to-peer media type. However,
SIP does not transport the media itself: that is handled by
codecs within the communications programs or devices.
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