PhoneJack cards.
These ISA and PCI telephony cards allow VoIP and Video Conferencing
using the OpenH323 suite of applications with a standard
telephone handset (including making the phone ring for incomming calls,
allowing dialing via the telephone and using the phone's speaker and mic
for the audio (freeing up the sound card).
They also feature a hardware G.723.1 audio codec making it easier to talk
to NetMeeting and H.323 users.