It includes H323 phone DLL, SIP Phone and Dialgo Tapi DLL
Research-Lab Telephony VoIP Suite is a free to try software. You can free download and try it for an evaluation period.
Dialgo VOIP TAPI DLL SDK
Telephony Control for Caller ID Extraction, Wave Playback & Recording on Modem
Vbuzzer Messenger 2.5.092
All in one instant messaging software that support VoIP, internet fax, RSS, video conferencing, and support Windows Live Messenger, Yahoo Messenger, AIM and ICQ. VoIP features include free internet calls, low cost PC to phone and phone to PC calls.
SIP Phone DLL 3.0
SIP Phone DLL - A powerful and highly versatile VoIP SDK. Our SIP Phone DLL provides a powerful and highly versatile solution to add quickly SIP (Session Initiation Protocol) based dial and receive phone calls features in your software applications.
OfficeSIP Server 1.0
Enable your employees call each other for absolutely free no matter where they are in the world. Use regular telephones, including wireless handsets or headsets, and don’t pay a penny for long-distance calls!