It's done in the init string (initialization string) and I believe its L0 (the letter "L" + number 0 or zero). Valid numbers are 0 thru 3 usually and L is for "loudness". Depending on your OS, there should be an option to add commands to the default string. It may be that your modem needs to be recognized exactly to make this work.
I know this has been asked many times before but I could not locate a discussion on it. I have disabled the modem speaker, and turned the speaker volume slider to OFF. Neither of these have silenced the dialing sound, or that annoying modem screech. Where is the other setting located?....I know it's there somewhere.

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