[MSDN Library April 2000] Buttons (14.2165005537099%)
MSDN Library - April 2000 > Platform SDK > Networking and Directory Services > Telephony Application Programming Interfaces (TAPI, TSPI, MSPI) > TAPI Service Providers > Telephony Service Providers (TSP) > Telephony Service Provider Interface (TSPI) > Phone Devices > Supplementary Phone Services