MITSUBISHI ELECTRIC MIM-G01 - Manual (Page 59)

AT+ T Speaker - Adjusting the Modem Speaker Volume
Appendix AT Commands MIM-A01
Mitsubishi Industrial Modem 8 - 25
AT+T Speaker="Volume"
Sets the volume level of the modem speaker.
Volume:
Volume switches the speaker off
Min low volume level (default)
Middle medium volume level
Max maximum volume level
Example:
AT+T Speaker="Middle"
Modem reply: OK
AT+T Speaker?
Displays the speaker settings.
AT+T Speaker?
Modem reply:
+T Speaker: "Off"
OK