You must add a VoiceProfile key value to the INF that installs a voice modem. Unimodem/V uses the bit settings in the VoiceProfile key to determine the capabilities of your voice modem. See Windows 95 Modem Registry Reference for a list of all the bit settings you can use. A Profile Calculator tool is included in the MDK that presents a graphical user interface with which you can build and analyze VoiceProfile vectors.
The example value used in SMPVOICE.INF is
HKR,, VoiceProfile, 1, 27,02,40,00
The value for the VoiceProfile key, 00400227, comes from adding the following flags:
0x00400000 Indicates the speakerphone cannot be muted.
0x00000200 Forces blind dialing after dialtone detection.
0x00000020 Modem uses the serial wave driver for playing audio to handset and line.
0x00000004 Modem has a speakerphone.
0x00000002 Modem can play audio to handset
0x00000001 This is a voice modem (this flag must always be set in the VoiceProfile
value).