Chapter 6 - Leased Line Operation; Connecting To A 2-Wire Leased Line; Leased Line Handshaking - ZyXEL Communications Omni 288S User Manual

Chapter 6 - Leased Line Operation

A leased line is a permanent telephone line connection between two fixed points.
It can be dedicated copper wires or a leased telephone circuit from the telephone
company. 4-wire leased lines use one pair of wires to transmit data and a second
pair to receive. 2-wire leased lines transmit and receive on the same pair of
wires. The Omni 288S supports only 2-wire leased lines.

Connecting to a 2-Wire Leased Line

The Omni 288S is equipped with a phone jack for dial-up line connections.
Connections can also be made to a 2-wire leased line using the same jack.
Line Type Setting
AT-Command
AT&L1
For the normal dial-up line only models, only 2-wire leased lines can be used and
the same phone jack is used for both dial-up and leased-line connections. The dial
backup feature is not available in this case.
Power Level Setting
The Omni 288S's leased-line mode transmission power level can be adjusted
from 0 dBm to -27 dBm in 1 dBm increments. If a dial-up model is used for 2-
wire leased-line connection, the transmission power is limited to -3 dBm.
AT-Command
AT*P0
AT*P15

Leased Line Handshaking

In a typical dial-up connection, the originating modem dials the number and waits
for the answering modem's carrier signal. The answering modem can be
commanded to either answer the call immediately, or after a specified number of
rings.
In a leased-line connection, the communication circuit between two modems is
always present. Dialing and waiting for rings does not occur in this situation. If
these two modems want to establish a data link, one must be designated as the
Chapter 6 - Leased Line Operation
Description
The modem is connected to a 2-wire leased
line; the line plug should be plugged into the
jack assigned LEASED LINE on the rear
panel.
Description
The default is -9 dBm. The adjustable range
is from 0 to -15 dBm, effective in leased-
line operation only. If bit 3 of S35 is set,
this range will change to -12 to -27 dBm.
6-1