Freeware: Vonage

Voicent Phone Appointment Reminder 5.2.1Easy to use automatic telephone notification software with confirmation and built in calendar. Ideal for time sensitive customer based organizations and professional offices. The reminder messages can be personalized with text to speech feature.

Voicent BroadcastByPhone Autodialer 5.4.2PC to Phone Auto Dialer Telephone Voice Recording Broadcast. Ideal for group event reminders, marketing, political campaign promotion, emergency notification and more. Spreadsheet interface makes it easy to create or import phone list.

Buzzfon p2p 0.21Buzzfonp2p is the latest voip software or peer to peer application that you can now download for free to call unlimited worldwide!

3CXPhone FREE VoIP Phone for Windows 4.0Free VOIP / SIP phone (softphone) for Windows. Use your PC as a phone. Works with popular VOIP providers and SIP PBX's (including 3CX Phone System). Easy to use&light weight. Full version, not a lite version! Free download from http://www.3cx.com