Telos TWOx12 - Page 203

TELOS TWOX12 USER’S MANUAL
GLOSSARY OF TELEPHONE TERMINOLOGY
APPENDIX 4 191
Dedicated Digital Service
- a “Hardwired” or “Nailed Up” digital circuit which is
permanently connected between 2 points. Typically 56Kbps or 64Kbps. Dedicated
digital lines are frequently cheaper than ISDN for full time service. Also called Digital
Data System.
DID
- Direct Inward Dialing. The ability for an outside caller to dial to a PBX extension
without going through an attendant or auto-attendant.
DID Extension
or DID station- A specific phone within a PBX which can be called
from the public telephone network without going through an attendant or auto-
attendant.
DID Number
- A phone number used to route calls from the telephone network to a
specific phone in a PBX (the DID extension). DID requires special DID trunks or
ISDN PRI “two-way DID” trunks. Blocks of DID numbers (typically 10 or 20) are
purchased from the LEC or CLEC for use on the PBX. The number of DID numbers
usually substantially exceeds the number of trunks in the system.
DID Trunk
- A Direct Inward Dialing Trunk. A trunk (channel) which can only receive
calls. A group of telephone numbers (DID numbers) are associated with a given trunk
group, however there is no one-to-one correspondence between the individual channels
and these numbers. The PBX uses the DID number given it by the phone company to
route the channel to the correct DID extension within the PBX extension. This allows
some or all PBX stations to receive calls directly without going through an attendant
(or auto attendant) Note that there are almost always more DID numbers than there are
DID trunks. See DID number and DID extension.
Direct Inward Dialing
- See DID
Directory Number
- Your seven digit telephone number (without the area code), as
found in the telephone directory.
Directory 1&2
(Zephyr)- The Utility menu on the Zephyr where the 7 digit Directory
Numbers can be entered during set up. The Zephyr generally does not require these
numbers.
DSL
- Digital Subscriber Line. Typically refers to an ISDN line or a T1 line, although
the term is also frequently used to mean the next generation beyond ISDN. Sometimes
xDSL is used to indicate that the writer is referring to any of a number of emerging
DSL technologies.
DSU
- Data Service Unit. See CSU/DSU.
DTE
- Data Terminal Equipment- When using serial communications such RS-232,
V.35, or X.21, the DTE is the device sending/receiving from a modem or CSU/DSU. In
contrast to DCE.
DTMF
– Dual Tone Multi Frequency. The standard tone-pairs used on telephone
terminals for dialing using in-band signaling. The standards define 16 tone-pairs (0-9,
#, * and A-F) although most terminals support only 12 of them (0-9, * and #). These
are also sometimes referred to as “Touch Tones”. Note that while digital data terminals
have the same symbols, ISDN uses “common channel signaling” (over the D channel)
and therefore does not necessarily generate any tones at all. However many terminal
still generate the tones since they will still be used on occasion to access services (such
as voicemail or automated attendant) at the far end using in-band tones.