Adding Registry Keys to Support Phone Message Recording and Playback

To support the telephone answering machine functions of recording incoming phone messages and playing the messages back through the handset when there is no active call, you must use your modem INF file to put values in fourteen different registry keys:

Registry Key	Value
AbortPlay	Command that stops playing audio data immediately (does not play the rest of the audio buffer contents). This command is not used for modems that are not using a serial wave device.
CloseHandset	Command that resets the modem to Class 0.
HandsetSetPlayFormat	Command that sets the modem's handset playback format.
HandsetSetRecordFormat	Command that sets the modem's handset recording format.
LineSetPlayFormat	Command that sets the modem's line playback format.
LineSetRecordFormat	Command that sets the modem's line recording format.
OpenHandset	Command that puts modem in a mode that enables audio to be played back through the handset when there is no active call.
StartPlay	Command that starts playing audio (wave files) out of the modem. If a serial wave driver is being used, a bit in the VoiceProfile key controls whether the baud rate is set prior to the StartPlay command or after the StartPlay command.
StartRecord	Command that starts recording audio (wave files) from the modem. If a serial wave driver is being used, a bit in the VoiceProfile key controls whether the baud rate is set prior to the StartRecord command or after the StartRecord command.
StopPlay	Command that can be used to reset the modem's baudrate after an AbortPlay or TerminatePlay command. A bit in the VoiceProfile key indicates whether Unimodem/V has to reset the UART's baudrate.
StopRecord	Command that stops recording audio (wave files) from the modem. If a serial wave driver is being used, a bit in the VoiceProfile key controls whether the baud rate is set prior to the StopRecord command or after the StopRecord command.
TerminateRecord	Command that causes the modem to finish recording its local buffer and stop recording audio data. This command is not used for modems that are not using a serial wave device.
TerminatePlay	Command that causes the modem to finish playing the contents of its local buffer and stop playing audio data after that. This command is not used for modems that are not using a serial wave device.

The relationship between these commands and the way they are used in sequence by Unimodem/V is shown in the following state transition diagram.

The following conventions are used in the illustration:

Italics = Registry key

Bold caps = State name

Underline = TAPI or MMSystem function called to cause state change

Non-bold caps = Parameters for TAPI functions

SMPVOICE.INF is a sample INF file in the MDK for a voice modem that uses the serial wave driver for playing audio to the handset and line. The example values from SMPVOICE.INF for the fourteen keys listed in the table above are:

   HKR, CloseHandset,            1,, "at#cls=0cr"
   HKR, StartPlay,               1,, "at#vtxcr"
   HKR, StopPlay,                1,, "None"
   HKR, StopPlay,                2,, "NoResponse"
   HKR, StartRecord,             1,, "at#vrxcr"
   HKR, StopRecord,              1,, "None"
   HKR, StopRecord,              2,, "NoResponse"
   HKR,, TerminateRecord,,       "
<h10>Ecratcr"
   HKR,, TerminatePlay,,         "
<h10>
<h03>atcr"
   HKR,, AbortPlay,,             "
<h10>
<h18>atcr"
   HKR, LineSetPlayFormat,       1,, "at#vls=0cr"
   HKR, LineSetRecordFormat,     1,, "None"
   HKR, LineSetRecordFormat,     2,, "NoResponse"
   HKR, HandsetSetRecordFormat,  1,,"at#vsr=7200cr"
   HKR, HandsetSetRecordFormat,  2,,"at#vbs=4cr"
   HKR, HandsetSetPlayFormat,    1,,"at#vsr=7200cr"
   HKR, HandsetSetPlayFormat,    2,,"at#vbs=4cr"
   HKR, OpenHandset,             1,, "at#cls=8cr"
   HKR, OpenHandset,             2,, "at#vls=2cr"