Farallon Communications 412, 612 manual Modem basics, Operating modes

A-2 Netopia ISDN Modem User’s Guide

Modem basics

A modem provides computer-to-computer communications over telephone lines. It acts like a telephone by dialing and answering calls. Your Netopia ISDN Modem uses digital technology to connect to the public telephone network. Yet, like analog modems, you use standard AT commands to communicate with the ISDN modem.

Operating modes

Command mode allows the Netopia ISDN Modem to accept operating commands and configuration settings from the keyboard. The ISDN modem enters command mode when:

■Power is applied (hardware reset)

■No carrier is detected

■The ISDN modem's carrier is lost

■The escape sequence (+++) is issued

In online mode, the Netopia ISDN Modem is “on-line” and sends any data it receives from your computer out to the remote ISDN device. The ISDN modem attempts to go into online mode when:

■The AT dial command ATD is issued for originating a call

■The AT answer command ATA is issued for answering a call

The escape sequence (+++) allows you to switch from online mode to command mode without breaking an established connection with a remote ISDN device. The ATO command returns the ISDN modem to online mode.