An open source communications platform, Asterisk® is a complete IP PBX in software. It runs on a wide variety of operating systems including Linux, Mac OS X, OpenBSD, FreeBSD and Sun Solaris and provides all of the features you would expect...
With Skype you can make free calls over the internet to other people on Skype for as long as you like, to wherever you like. It is free to download. You can also call landlines and mobiles at great rates.
Twilio allows your web application to easily make and receive phone calls and SMS text messages using a simple web service API and basic web programming skills like HTTP, XML, and REST. You can build hosted IVR, PBX and SMS applications wi...
Vonage is a leading provider of VoIP internet broadband telephone services. Vonage offers VoIP calling plans to home, residential and business customers who wish to have unlimited long distance with cheap international calling rates.
ooma.com - Breakthrough Reliable VoIP frees US calling and delivers premiere digital telephony, including screenable broadband voicemail, 2 lines, Caller-ID and way more.