PHONEFEATURE_ Constants
The PHONEFEATURE_ constants list the operations that can be invoked on a phone using this API. Each of the PHONEFEATURE_ values corresponds to a TAPI function with an identical or similar name. 
- PHONEFEATURE_GETBUTTONINFO
- 0x00000001
 phoneGetButtonInfo
- PHONEFEATURE_GETDATA 
- 0x00000002
 phoneGetData
- PHONEFEATURE_GETDISPLAY
- 0x00000004
 phoneGetDisplay
- PHONEFEATURE_GETGAINHANDSET 
- 0x00000008
 phoneGetGain PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_GETGAINSPEAKER 
- 0x00000010
 phoneGetGain PHONEHOOKSWITCHDEV_SPEAKER
- PHONEFEATURE_GETGAINHEADSET 
- 0x00000020
 phoneGetGain PHONEHOOKSWITCHDEV_HEADSET
- PHONEFEATURE_GETHOOKSWITCHHANDSET 
- 0x00000040
 phoneGetHookSwitch PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_GETHOOKSWITCHSPEAKER 
- 0x00000080
 phoneGetHookSwitch PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_GETHOOKSWITCHHEADSET 
- 0x00000100
 phoneGetHookSwitch PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_GETLAMP 
- 0x00000200
 phoneGetLamp
- PHONEFEATURE_GETRING 
- 0x00000400
 phoneGetRing
- PHONEFEATURE_GETVOLUMEHANDSET
- 0x00000800
 phoneGetVolume PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_GETVOLUMESPEAKER 
- 0x00001000
 phoneGetVolume PHONEHOOKSWITCHDEV_SPEAKER
- PHONEFEATURE_GETVOLUMEHEADSET 
- 0x00002000
 phoneGetVolume PHONEHOOKSWITCHDEV_HEADSET
- PHONEFEATURE_SETBUTTONINFO 
- 0x00004000
 phoneSetButtonInfo
- PHONEFEATURE_SETDATA 
- 0x00008000
 phoneSetData
- PHONEFEATURE_SETDISPLAY 
- 0x00010000
 phoneSetDisplay
- PHONEFEATURE_SETGAINHANDSET 
- 0x00020000
 phoneSetGain PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_SETGAINSPEAKER 
- 0x00040000
 phoneSetGain PHONEHOOKSWITCHDEV_SPEAKER
- PHONEFEATURE_SETGAINHEADSET 
- 0x00080000
 phoneSetGain PHONEHOOKSWITCHDEV_HEADSET
- PHONEFEATURE_SETHOOKSWITCHHANDSET 
- 0x00100000
 phoneSetHookSwitch PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_SETHOOKSWITCHSPEAKER 
- 0x00200000
 phoneSetHookSwitch PHONEHOOKSWITCHDEV_SPEAKER
- PHONEFEATURE_SETHOOKSWITCHHEADSET 
- 0x00400000
 phoneSetHookSwitch PHONEHOOKSWITCHDEV_HEADSET
- PHONEFEATURE_SETLAMP 
- 0x00800000
 phoneSetLamp
- PHONEFEATURE_SETRING 
- 0x01000000
 phoneSetRing
- PHONEFEATURE_SETVOLUMEHANDSET 
- 0x02000000
 phoneSetVolume PHONEHOOKSWITCHDEV_HANDSET
- PHONEFEATURE_SETVOLUMESPEAKER 
- 0x04000000
 phoneSetVolume PHONEHOOKSWITCHDEV_SPEAKER
- PHONEFEATURE_SETVOLUMEHEADSET 
- 0x08000000
 phoneSetVolume PHONEHOOKSWITCHDEV_HEADSET
  Windows NT/2000: Requires Windows NT 4.0 SP3 or later.
  Windows 95/98: Requires Windows 95 or later.
  Version: Requires TAPI 2.0 or later.
  Header: Declared in Tapi.h.