Glossary
GL-4
Cisco ATA 187 Analog Telephone Adaptor Administration Guide for SIP (Version 1.0)
OL-21862-01
IP
Internet Protocol. Network layer protocol in the TCP/IP stack offering a connectionless internetwork
service. IP provides features for addressing, type-of-service specification, fragmentation and
reassembly, and security. Defined in RFC 791.
IVR
Interactive voice response. Term used to describe systems that provide information in the form of
recorded messages over phone lines in response to user input in the form of spoken words or, more
commonly, DTMF signaling.
L
LDAP
Lightweight Directory Access Protocol
LEC
local exchange carrier
Location Server
A SIP redirect or proxy server uses a location server to get information about a caller’s location.
Location services are offered by location servers.
M
MWI
message waiting indication
µ
-law
North American companding standard used in conversion between analog and digital signals in PCM
systems. Similar to the European a-law. See also a-law and companding.
N
NAT
Network Address Translation. Mechanism for reducing the need for globally unique IP addresses.
NAT allows an organization with addresses that are not globally unique to connect to the Internet by
translating those addresses into globally routable address spaces. Also known as Network Address
Translator.
NSE packets
Real-Time Transport Protocol (RTP) digit events are encoded using the Named Signaling Event (NSE)
format specified in RFC 2833, Section 3.0.
NAT Server
Network Address Translation. an Internet standard that enables a local-area network (LAN) to use one
set of IP addresses for internal traffic and a second set of addresses for external traffic.
NTP
Network Time Protocol. Protocol built on top of TCP that assures accurate local time-keeping with
reference to radio and atomic clocks located on the Internet. This protocol is capable of synchronizing
distributed clocks within milliseconds over long time periods.
P
POTS
Plain old phone service. Basic phone service supplying standard single-line phones, phone lines, and
access to the PSTN.