Dial Backup and Leased-Line Restoral

Chapter 4 - Leased Line Operation

For four-wire leased line operation, the MT5600BA-V.92 modem has a dial backup capability, in which the modem is connected to a standard dial-up line as well as to the leased line. If the leased line fails, the originate modem automatically dials and connects to the answer modem through the standard telephone network. While it is in dial backup mode, the modem periodically checks the leased line to see if it is operational. If the line is operational, the modem then attempts to restore the leased line. If the modem detects that it is not connected to the standard telephone network when the leased line fails, it immediately switches to leased line restoral.

The dial-back timer, register S17, determines how long the modem waits after a leased line failure before it attempts a dial backup connection. The S17 default setting is one minute. During that minute, the originate modem tries to establish the leased line link. If the leased line is established during that time, the S17 timer is cleared and everything is back to normal. If the timer expires, the modem attempts a dial backup connection. The purpose of the timer for the answer modem is to determine when it can accept a dial-up call. Dial-back starts only when both timers have expired and the leased line is still down.

The restore timer, register S15, determines how frequently restoral attempts occur when the modems are in dial backup mode. S15 can be set from 10 to 255 minutes in one minute increments. A value of 0 disables dial backup. The default value is 30 minutes.

Note: Register S15 must be set identically on the local and remote modems.

The dial backup number must be set from the front panel of the modem.

Dial Backup and Leased Line Restoral Setup

1.Connect a modular telephone cable to the LINE jack of an MT5600BL modem set up for four-wire leased line operation. Connect the other end of the cable to a standard dialup line jack.

2.Turn on the modem.

3.Starting at the STATUS screen, press the following buttons on the front panel: , , ◊, , ◊, ◊, ◊. The ENTER NUMBER screen appears.

4.Press the 〈⇓ or  button several times to select the first digit in the dial backup telephone number.

5.Press the ◊ button to go to the next digit in the number.

Note: To backspace or to cancel an entry, press ◊ several times.

6.The number can be up to 30 characters in length. Repeat steps 4 and 5 until the number is entered, and then press the Enter button to store it. The DIAL BACK- UP # STORED screen appears.

7. Press the Enter button again to go to the DIAL BACKUP NUMBER screen.

Note: Steps 8 through 15 are optional.

MT5600BA/BL Series User Guide