User manual

CHAPTER 4: GENERAL INFORMATION AND FEATURES

4.1 Preview

In order to help you to get familiar with your Network Series Modem, this

chapter introduces you some common applications. For most applications, the

materials of this chapter will be enough.

4.2 Dial Line VS. Leased Line

There are two kinds of telephone lines --- dial lines and leased lines described as

below.

A. 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

B. B. 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

PSDN

FIG 4-2: Dial Line