This glossary provides definitions of some common of the terms that are used in the telecommunications industry.
Term |
Definition |
10Base-T |
10 Mbps |
100Base-T |
100 Mbps |
1000Base-T |
1000 Mbps |
4E |
Class 4 switch from Lucent Technologies. One that generally provides call routing between carriers. |
5E |
Class 5 switch from Lucent Technologies. One that generally provides connectivity to end users. |
ACD |
Automatic Call Distribution. A telephone system feature which distributes incoming calls to an agent or representative and keeps statistics on each call. Typically used in high-volume call center environment. |
Analog |
Phone line using an |
ANI |
Automatic number |
Automated Attendant |
Voicemail-based menu tree that helps direct |
Automatic Call Distribution |
See ACD. |
Blue Lights |
Slang; see Emergency Phones. Also, the actual blue light on top of an Emergency phone. |
Call Forwarding |
Service to send calls to another location, available in |
Centranet |
Phone switching |
Centrex |
Phone switching |
CSU |
Channel service unit. Used |
DHCP |
Dynamic Host Configuration |
DID |
Direct Inward Dialing. The service provided by a network service vendor (like AT&T), which allows a caller to dial a 10-digit telephone number and reach an individual extension of a business communications system. |
Direct Inward Dialing |
See DID. |
Direct Outward Dialing |
See DOD. |
DOD |
Direct Outward Dialing. A feature that allows telephone system users to dial an access code and a telephone number from their desk. |
DS0 |
Network facility with |
DS1 |
Network facility with |
DS3 |
Network facility with |
DTMF |
Dual-tone multi-frequency |
E Phone |
Slang. See Emergency |
Elevator Phones |
Phones on the same system |
Emergency Phones |
Specialized phones that will automatically call the Department of Public |
EPN |
Extended Port Network. A remote switching module of a telephone switch. Different vendors use different names. EPN is specific to Avaya and our Definity line of PBXs. |
ESF |
Extended Super Frame T1 |
Ethernet |
Local area network used |
Extended Port Network |
See EPN. |
Ground Start |
Way of signaling |
IP |
Internet Protocol. A standard addressing scheme and message routing protocol for communication between nodes of a data network. |
ISDN Line |
Integrated Services |
Loop Start |
Way of signaling |
MLHG |
Multi-Line Hunting. The |
OC-1 |
Optical Carrier using a |
OC-3 |
Optical Carrier using a |
OC-12 |
Optical Carrier using a |
OC-48 |
Optical Carrier using a |
PBX (also called PABX) |
Private Branch Exchange. A telephone switching system usually installed at a business location as opposed to a service providers central office. |
PDN |
Primary Directory Number. The telephone number that the physical telephone set is associated with. Generally, the first telephone number listed on a multi-line set. |
PDN (alt.) |
Public Data Network. A digital data network, usually X.25 protocol that is accessible by dialing a public telephone number. |
Primary Port Network |
See PPN. |
Private Branch Exchange |
See PBX. |
SDN |
Secondary Directory Number. A telephone number that is picked up on a telephone set, but which is a PDN on another instrument. |
SDN (alt.) |
Software Defined Network. A virtual private network. |
SLA |
Service-Level Agreement |
SNI |
Switch Node Interface. The link(s) between a PPN and an EPN over which control information is passed. Phone calls can be routed over these facilities as well, but this is generally not the case at USC. |
Sonet |
Synchronous Optical |
Stations |
In the voice world, a |
Switch module |
Generic term |
Switch Node Interface |
See SNI. |
T1 |
Network facility with |
T3 |
Network facility with |
TCO |
Total Cost of Ownership. |
TCP/IP |
Transmission Control |
TG |
Trunk Group. A quantity of network facilities that complete calls. |
Tie |
Also, Tie Line. A specific type of trunk that is used to connect two switches. |
Trunks |
Individual channels or circuits that can be grouped. This is the smallest denominator for a network facility. |
Umbilicals |
Specialized connections between a remote module(s) and the main host in the 5ESS switch. Similar to a SNI facility, these carry control information. |
Voicemail System |
System that specifically |
VoIP |
Voice over IP. A technique |
VPN |
Virtual Private Network. |
WAN |
Wide Area Networking. |