Cisco SIP IP Phone Administrator's Manual page 184

Glossary
S
Session Initiation Protocol. This is a protocol developed by the IETF MMUSIC Working Group as an
SIP
alternative to H.323. SIP features are compliant with IETF RFC 2543, published in March 1999.
SIP equips platforms to signal the setup of voice and multimedia calls over IP networks.
Service provider interface.
SPI
T
Time-division multiplexing. Technique in which information from multiple channels can be allocated
TDM
bandwidth on a single wire, based on preassigned time slots. Bandwidth is allocated to each channel
regardless of whether the station has data to transmit.
U
See UAS.
user agent
User agent client. A user agent client is a client application that initiates the SIP request.
UAC
User agent server (or user agent). A user agent server is a server application that contacts the user when
UAS
a SIP request is received, then returns a response on behalf of the user. The response accepts, rejects,
or redirects the request.
V
Voice over IP. The ability to carry normal telephone-style voice over an IP-based Internet with
VoIP
POTs-like functionality, reliability, and voice quality. VoIP is a blanket term, that generally refers to
the Cisco standards-based (for example H.323) approach to IP voice traffic.
Cisco SIP IP Phone Administrator Guide
GL-4