The LAL (Local Analog Loopback) tests whether the modem is passing error-free data to and from the locally-connected computer.
To run an LAL test:
1. Remove the telephone line connector from the modem's line input connector.
2. Run a communications application that provides a terminal emulation mode. For example, the minicom application, found on computers that have Red Hat, offers terminal emulation mode.
3. Issue the AT&F command to set the modem to factory default options. OK appears.
4. Issue the ATS46=23 command.
5. Issue the AT&T1 command (the characters may not appear as you type). Wait for ten seconds.
6. Begin typing on the keyboard. The characters you type should appear.
7. Enter +++ OK appears.
8. Enter the ATH (hang up) command to end the LAL test.
If the characters that you typed did not appear properly, close running applications and restart the computer. If you find the same communications problem, report the problem to your personal computer or modem vendor.