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3CX VOIP PBX - provides an easy to use, plug and play SIP - IP PABX for Windows. With a software based IP PBX you will save on PBX maintenance and halve your phone bill. Download the FREE edition today and break free from your proprietary phone syste...

Office SIP Server is free VoIP and Instant Messaging Software

Asterisk is free software that transforms a computer into a communication server. Asterisk lets you build applications like PBX, VoIP gateway, IVR and ACD.

Welcome to voip.about.com, your guide site to everything Voice Over IP, also called VoIP, IP Telephony or Internet Telephony. Learn how to make free or cheap local and international calls using your PC or phone. Stay updated on VoIP hows and whats, V...

Comprehensive links to information and resources about the Linux Operating System.

The Award Winning Business Phone Service over the Internet. OnSIP business VoIP service is a hosted pbx system that allows you to streamline your business communications. There’s no phone company hassle, no phone system to buy or manage, no contracts

SourceForge.net. Fast, secure and free downloads from the largest Open Source applications and software directory

Voxilla has been a trusted source for accurate, up-to-date information on the IP Communications industry since 2002. A dedicated staff of reporters and engineers produce feature articles and product reviews to keep industry watchers abreast of the p...