ADTRAN Express 4110 User Manual page 189

T1
Also T-1. A digital transmission link with a capacity of 1.544 Mbps. T1 uses two pairs
of normal twisted wires. T1 normally can handle 24 voice conversations with each
conversation being digitized at 64 kbps. With more advanced digital voice encoding
techniques, it can handle more voice channels. T1 is a standard for digital transmission
in North America.
TA
Terminal Adaptor. A DCE that connects to the ISDN S-Interface and enables non-
ISDN terminal equipment to communicate over the ISDN.
TE1
Terminal Equipment Type 1. ISDN-compatible terminals.
Telnet
The TCP/IP standard protocol for remote terminal connection service. Telnet allows
a user at one site to interact with a remote timesharing system at another site as if the
user's terminal were connected directly to the remote machine.
TCP/IP
Transmission Control Protocol/Internet Protocol. A set of protocols developed by the
Department of Defense to link dissimilar computers across many kinds of networks.
twisted pair
Two wires twisted around each other to reduce induction (interference) from one wire
to the other. Several sets of twisted pair wires may be enclosed in a single cable. Twist-
ed pair is the normal cabling from a central office to your home or office, or from your
PBX to your office phone. Twisted pair wiring comes in various thicknesses. As a gen-
eral rule, the thicker the cable is, the better the quality of the conversation and the long-
er cable can be and still get acceptable conversation quality. However, the thicker it is,
the more it costs.
2B+D
The Basic Rate Interface (BRI) in ISDN. A single ISDN circuit divided into two 64 kbps
digital channels for voice or data and one 16 kbps channel for low speed data (up to
9,600 baud) and signalling. 2B+D is carried on one or two pairs of wires depending
on the interface, the same wire pairs that today bring a single voice circuit into your
home or office. See ISDN.
23B+D
In ISDN, also known as the Primary Rate Interface. A circuit with a wide range of fre-
quencies that is divided in twenty-three 64 kbps paths for carrying voice, data, video,
or other information simultaneously. It bears a remarkable similarity to today's T1
link, except that T1 carries 24 voice channels. In ISDN, 23B+D gives twenty-three
channels and one D channel for out-of-band signalling. However, in T1, signalling is
handled in-band. See ISDN.
two-wire circuit
A transmission circuit composed of two wires, signal and ground, used to both send
and receive information. In contrast, a 4-wire circuit consists of two pairs. One pair
is used to send and one pair is used to receive. All trunk circuits (long distance) are
61200176L3-1 Express 4110/4120 User Manual
Glossary
Glossary-7