How do I disable the modem speaker when answering faxes with Mac OS X?

Using Mac OS X's Built-in Fax System:
* In order to disable the modem speaker when answering faxes using Mac OS X's built-in fax system, you must modify the file /etc/efax.rc which requires administrator privileges.

1) Edit the file /etc/efax.rc. For example, from Terminal.app (the command line application), you may use "sudo vi /etc/efax.rc". If you have TextWrangler or BBEdit installed, then you may open the file using either of those applications by selecting File-->Open File By Name and open the file "/etc/efax.rc".

2) Add or modify the SPKR string (if adding it, add it after the line "VCMD="):
SPKR="-iM0"

The -i means the commands following it are sent before the modem is put into fax mode. See http://www.manpages.info/macosx/efax.1.html for more info.

 For reference, various versions of the efax.rc file from various versions of Mac OS X may be found by browsing Apple's source code repository (in case you need to see how the file originally looked):
https://opensource.apple.com//source/efax/

3) Save efax.rc and then disable receiving faxes via Print & Fax pane of System Preferences (and click on OK after disabling it--clicking on OK causes the OS to send commands to the modem and causes the DTR LED on the modem to turn off). Now re-enable receiving faxes via Print & Fax pane of System Preferences (and click on OK after enabling it--clicking OK causes the OS to send commands to the modem and causes the DTR LED on the modem to turn on). You may need to disable and enable the receive setting a couple of times to make sure that efax starts sending the new init string.


Using Other Fax Software:
* Add the following command to the initialization string: M0
* Some software may send certain commands at different times during initialization before/after a call. In this case, try using "-iM0".


Command:     M (Monitor Speaker Mode)
Description: Turns the speaker on and off.
Syntax:      ATM
Values:      0 Speaker always off.
             1 Speaker on until carrier signal detected.
             2 Speaker always on when modem is off-hook.
             3 Speaker on until carrier is detected, except while dialing.
Default:     1