VOIP software uses voice over internet protocol and the voice signal is transmitted over the Internet or Packet Switched Network instead of PSTN(Public Switched Telephone Network).Voip software can be developed in many ways – i.e based on proprietary or open protocols.e.g IMS(IP Multimedia Subsystem),RTP(Real Time Protocol),SIP(Session Initiation Protocol)…and so on.Here is the two best and free voip software for internet calls on the windows platform.
VOIP Software for Windows 7
#1. Skype : It’s available free for instant messaging,voice calls(Audio and video calls),video conferencing(With Some limit),file sharing and other lot of features are available.For other features like calling PC to phone,is not free instead you need to buy skype credit by using Paypal.Some other features include HD video quality,Call Transfer,so on.Skype 4.2 version is available for windows.To install skype on windows 7,First download and then double click;follow the instruction on the screen and enjoy Skype!!
#2. Google Talk(Gtalk) : It’s a great application that uses XML and XMPP based protocol like jabber and very good for text message(with lot of fun) chat,voice calls,for sharing files with your friends…and so many fun with no cost at all.Download Gtalk and install to enjoy goggle Talk.
funny, you mention 2 programs that are chat programs with audio capabilities while VOIP is something slightly different and can not easily be done with skype or gtalk.
If you want to use voipbuster or your own asterisk server etc, you better get something like the 3cx softphone which is for VOIP calling rather them IM.