Nokia 2720 Flip Phone - Flip Phone - 2 Chips - GSM

The telephone is a communication device initially designed
to transmit the human voice and be able to communicate at a distance.


To work, the telephone requires a terrestrial or space infrastructure
, the telephone network. After connecting a
fixed terminal or turning on their mobile device, a user who has
taken out a subscription with a telecommunications operator can
make a telephone call to a recipient who is also connected by
dialing their assigned number, which usually
triggers the ringing of the destination device. If the person called accepts
the call, a phone conversation can begin.


With the exception of emergency calls made to special numbers
, calls made via a telephone have a cost, which is
determined by call rates established according to their duration, the location of
the recipient and the quality of the number.
Telephony is therefore an important market in the telecommunications sector
.


Mobile telephony was born in the
1950s in the United States. The first networks required the allocation
of one frequency per call, and the geographical areas were
large (few subscribers per unit area). Subsequently, cellular networks
allowed for a more rational use of frequencies,
thus considerably increasing the capacity of the networks.