If you use Windows, Linux or a Mac see the following softphones:

• For a Flash based softphone (Windows, Linux and Mac) with anytime, anywhere access (like webmail) try Flaphone (your settings will be stored on their servers, thus you only need to remember your username and password to use it from any machine and has support for the G.729 CODEC)
• For Windows Vista or Mac OS X you can also consider the X-Lite software phone, available for download here. The commercial editions with the G.729 CODEC (Bria or eyeBeam) will provide optimal use of low bandwidth situations and assure good quality calls.
• For Windows, Linux and Mac you can also try Zoiper. Consider using commercial edition with G.729 CODEC.
• For all versions of Windows XP, Windows Vista, Windows CE, Mac and Linux try SJPhone.

(Refer to the respective websites for instructions on setup and compare the SIP settings you will set up with the settings on the home page of this site.)