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Chapter 4 General Information and Features
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4.2 Dial Line VS. Leased Line
There are two kinds of telephone lines --- dial lines and leased lines described as
below.
Leased line provides users a dedicated communication channel. Both ends of the
circuit are permanent. It offers continuous service and provides absolute security.
It will not be invaded by any other circuit due to the dedication, it supports better
quality and higher reliability.
DTE
MODEM MODEM
DTE
∼
FIG. 4-1: Leased Line
Before using a dial line such as the circuits for telephone and facsimile machine,
we have to dial a number. For the users who are used to communicate with
different counterparts such as bulletin board system (BBS), public service network,
and toll free services, this will be a better choice. Due to the time consuming
dialing procedure (45-60) Sec.), the efficiency is lower than that of leased lines. It
is even worse when line or destination is busy. Furthermore, the communication
path is different at each dial, so the line quality is not ensured. Besides, it doesn’t
guarantee good security.
To make this modem operate in 2/4-wire leased line, or dial line, you need to do
some settings with Line Type Selection under “LINE SETUP” menu.
DTE MODEM MODEM DTE
DTE MODEM MODEM DTE
PSDN
FIG 4-2: Dial Line