All Hayes-compatible modems have registers that govern the modem's behavior. You can modify these registers and perform a variety of other tasks with Hayes commands.
In ClarisWorks, you can issue Hayes commands by choosing Connection from the Settings menu and selecting the Serial Tool. Then choose Open Connection from the Session menu.
Here is a sampling of some of the useful Hayes commands. Press return after each command to send it to the modem. If you find a command doesn't work for your modem, consult your modem manual. Modems can differ in how they implement commands. Where you see n, substitute a number. Zero generally means off. All 0 characters below are zeros unless otherwise mentioned.
AT - If you are connected to the modem properly, it will answer "OK."
ATDT - Dial a phone number (tone)
ATDP - Dial a phone number (pulse)
ATZ - Reset modem
AT&F - Restores the modem's original factory settings.
AT&V - Produces a screen dump showing the current modem register settings.
ATEn - Local echo. Substitute1 for n to turn it on, 0 to turn it off.
AT&K0 - Disable data compression for communicating with low-speed modems that you are having issues connecting with.
AT&M0 - Disable error correction for communicating with low-speed modems that you are having issues connecting with.
AT&D0 - Force on the Data Terminal Ready (DTR) signal. Can be helpful if you experience sudden hangups during file transmissions. The usual setting is AT&D2.
ATS110=0 - Disable V.32bis. Helpful if you are having issues connecting to a picky V.32 modem which lacks the additional bis protocol.
ATMn - Modem speaker volume
ATS0=n - Sets the number of rings on which to answer in Auto Answer mode.
ATS7=n - Sets the number of seconds the modem waits for a carrier. Default is usually 60. May need to be increased for international calls or numbers that don't answer immediately.
+++ - Escape to command mode. Enables you to switch to Hayes command mode while online.
ATO - Return to online mode. That's the letter O, not a zero! If this fails, try AT01 which returns online and asks both modems to resynchronize.