How do I configure the modem for voice and speakerphone operation?

You need to issue the command AT#CLS=8#VLS=6

#VLS=6 This command selects speakerphone mode while in #CLS=8 mode. This is a headset or speakerphone powered directly by the modem. When such a device is selected, the modem immediately enters Online Voice Command mode, DTMF monitoring is enabled if applicable, and the VCON response is sent.

Note: AT#VLS=6 results with ERROR if speakerphone is not supported.

#CLS=8 Voice/Audio Mode. #CLS is the main setting which the DTE uses to affect directed or adaptive answer or originate sequences involving voice modes. All telephone calls initialized by #CLS=8 result (after answer or successful call progress) in the modem operating in Online Voice Command Mode.

For more details go to our web site and download the #V Developers Kit at:
http://www.multitech.com/en_US/DOCUMENTS/Families/MultiModemZDX/manuals