Voice Basics

In Telecom basically we have two types of voice signals:

Analog and Digital.

Analog are of two types: Loop start and Ground Start

Loop Start is sued in home environment.

Ground start is used in PBX environment , it fixes the problem of glare.

Digital Signals are of two types:

Channel associated signaling (CAS): Signaling information is transmitted using
the same bandwidth as the voice.

■ Common channel signaling (CCS): Signaling information is transmitted using a
separate, dedicated signaling channel. ( If used with T1 only 23 channels can be used).

There are two types of Digital lines:

T1 24 channels and used in America and Japan
E1 32 channels (only 30 can be used) used in rest of the world.