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Command Your Modem With HyperTerminal

Once upon a time--before AOL, ISPs, and the Web--connecting to an online service like CompuServe, The Well, or MCIMail required an artifact called communications software. If you're a relative PC geezer like me, you may remember some of the leading titles--Procomm Plus, Smartcom, and HyperTerminal. Wait a minute, that last one sounds familiar... yup, it still shows up in Windows under Start, Programs, Accessories, Communications. (The exact location may be different on your machine, but all versions of Windows from Windows 95 forward include a copy of HyperTerminal.)

Since communications programs are unnecessary for browsing the Web, downloading files, or reading e-mail, you might be tempted to uninstall HyperTerminal. Don't. Though your Web browser is good for a lot of things, it can't talk directly to your modem. In addition, your Web browser isn't a Telnet client--a device that provides the most basic means of connecting to other computers (Unix servers) over the Internet--though it can launch one as a helper application.

In most cases modems work just fine as long as you have all the proper drivers installed for them. On certain occasions, however, you may find yourself faced with a situation where you need to enable or disable a particular modem feature, check its firmware version number or date, or command it to hang up. Fortunately, you can perform all of these tasks by employing the scores of AT commands described in your modem's manual. If frequent disconnections or slowdowns bedevil you, you may even be able to troubleshoot the problem by issuing an AT command to query the modem for its connection status.

It's quite easy to send AT commands to the modem from the command prompt (simply click Start, Run, then enter command) by using the echo command. For example, entering echo atz com1 sends the atz (reset) command to whichever device is connected to COM1. Unfortunately, this simple command-line trick is a one-way affair: You won't see the OK response the modem sends back; and if the modem is actually connected to COM2, not COM1, you won't know any different.

HyperTerminal gives you a two-way conduit to your modem, including serial-port ISDN modems. To create a connection to the modem, first launch HyperTerminal, then enter a name for the connection in the Connection Description dialog box. In the Connect To dialog box that appears next, choose the COM port your modem is connected to from the "Connect using" list, and then click OK. Set the connection speed in the next dialog box (anything up to 115200 is safe), click OK, and you should be connected. To issue an AT command, type the command and press Enter. Your modem should respond with "OK."