Telos TWOx12 - Page 202

TELOS TWOX12 USER’S MANUAL
GLOSSARY OF TELEPHONE TERMINOLOGY
APPENDIX 4 190
coded audio. Strictly speaking, a codec does not include an ISDN terminal adapter and
related equipment.
Combination Trunk
- A trunk (channel) which can both make and receive calls. This
generally refers to analog ground start or loop start trunks, although the term can be
applied to ISDN BRI or PRI channels as well. Each combination trunk normally has a
telephone number, although they are frequently part of a hunt group and only one
number may be published for that group. Also called a Both Way Trunk. This is not the
same as a Two-way DID trunk. See DID trunk, Hunt Group and Trunk.
Competitive Local Exchange Carrier
- See CLEC.
Concentration
- The basic premise is to share facilities wherever possible. For
instance, while there may be thousands of customers served by a given Central Office,
there will be substantially less than that number of calls which can be handled
simultaneously. And even fewer long distance calls can be made simultaneously. The
art of Traffic Engineering is to have enough capability that calls are rarely blocked, but
not any more than that. See also Choke Exchange and Blocking.
CPE
- Customer Premise Equipment- Customer owned equipment located at his/her
facility, such as a CSU or terminal. In the USA and Canada the NT1 is part of the
CPE.
CSD
- Circuit Switched Data- A dial-up data communications channel which, once
established, looks like a transparent data pipe. Also, the type of ISDN service required
to utilize this capability of an ISDN circuit. In contrast to CSV
CSU/DSU
- A device which incorporates the functions of a CSU (Channel Service
Unit) and a DSU (Data Service Unit) and interfaces between a Switched-56 (or
“Dedicated Digital Service”) line and a user’s data equipment such as the Zephyr.
CSV
- Circuit Switched Voice- A dial-up communications circuit for voice grade
communication. Also, the type of ISDN service required to use this capability of an
ISDN circuit. In contrast to CSD
Custom ISDN
- An ISDN protocol which pre-dates National ISDN-1. In most cases
National ISDN-1 is also available. The Northern Telecom DMS-100 switch Supports
“Custom DMS ISDN”. The AT&T/Lucent 5ESS switch Supports “Custom Point-to-
Point” (PTP) and Custom Point-to-MultiPoint (PMP). The ISDN protocol has no
relation to where one may call. The Zephyr does not support PMP.
D Channel
- Data/Delta Channel. Depending on who you ask. it is Data or Delta. The
channel which handles ISDN network-related data between the user’s equipment and
the Telco switch. Used to carry data to set up calls and receive calls. Some Telco’s
also allow users to use the D channel to access the packet data network, with
appropriate terminal equipment.
DCE
- Data Communication Equipment. When using serial communications such RS-
232, V.35, or X.21, the DCE is the device sending/receiving from the Telco line. i.e.: a
modem or CSU/DSU. In contrast to DTE.
DDS
- Digital Data System- See Dedicated Digital Service.
Dedicated Circuit
- A permanent channel between two locations. As opposed to a
Switched Circuit.