Callwave
Internet Answering Machine software uses Busy Call Forwarding to answer and record callers messages while you are on-line.

Internet Call Manager
An easy and inexpensive way to stay on-line as long as you want and never miss a phone call.

Pagoo
Answer calls and make long distance phone calls while online.

PalTalk.com
Enables live video calls, conference calls and voice chat-rooms.

PC-Telephone
Make free pc-to-pc and cheap pc-to-phone and pc-to-fax calls over the Internet and ISDN/PSTN telephone networks. Use your computer as internet telephone, ISDN phone, answer phone, caller id, fax software and voicemail client.

VocalTec
Enables voice and multimedia communications over packetized networks, the Internet and intranets.