Free voip on mac

hi
i am working on apple macbookpro for which i am looking for good communication application for voip. i armature user for mac os x and dont having much idea so please tell me a free application for voip on mac .
thank you

Gizmo is a VoIP software Free and easy to use. Gizmo Project uses your Internet connection (broadband or dial) to make calls to other computers. With a click of the mouse, the user is connected to friends, family and colleagues around the world and it's free (calls to users of the software). Note that the software has versions compatible with different operating systems: Windows, Macintosh and Linux.

try Asterisk, it is is an open source implementation (GPL) a PBX (Private Branch eXchange). Developed for Linux, Also runs on Asterisk OpenBSD, FreeBSD, Mac OS X, Solaris and Microsoft Windows. It supports protocols SIP and IAX.

Asterisk can be used with different softphones compatible SIP (Ekiga, Xten Lite ,...) or IAX (Kiaxi ,...).The Asterisk development is sponsored by the Society Digium. Digium is remunerated by the sale of PC cards for creating PCPBX using Asterisk.

my best one is LoudHush, this is a telephony software for Mac. It can connect to your company PBX or to a provider of voice over IP using the IAX protocol. Once connected, the software lets you make calls, put them on hold, receive and make transfers.

ohphoneX is software for video-conference. The application is compatible with the H.323 standard and can serve both professionals and individuals. You can configure multiple networks (home and work for example), with information stored in memory you can enable the data from that to which you are. You have an address book, to have faster access to your contacts. Note that you do not have to distribute video from your webcam, instead you can send a still image.

Most popular application is Skype to communicate with your family, whatever your location. Audio secure conversations, conference calls, exchange text messages, videoconferencing are the major features of this software.
Skype is very simple to implement, and its use is intuitive. get new version this new version, you'll find such improvements for video and sound, with a full-screen and a "smart aid" to resolve the sound problems during a call. Another function lets you switch quickly from one conversation to another, whatever the method of communication (call, video chat, etc..).