Linphone

Linphone is a versatile web phone that allows you to make calls to anyone in the world via the internet. The best part is that the cost of the call is the same as your internet connection costs. Simply provide Linphone with a SIP URL, such as [email protected], where "toto" is a Linux user running Linphone, and "machine.com" is the name of a host on a network. If you don't know the machine's name, an IP address in dot notation (like 192.0.0.1) works just as well.

Linphone is primarily SIP compliant, and it works well with various implementations, including eStara softphone for Windows, Pingtel phones, Hotsip for Windows, Vocal from Vovida (which includes a SIP proxy that works with Linphone), Siproxd (a free SIP proxy developed by Thomas Ries), and Partysip (a generic and fully functional SIP proxy). Although Linphone may be compatible with other SIP phones, this hasn't been tested yet.

Please note that Linphone utilizes the SIP protocol to establish calls, so it is not compatible with H323 phones like Netmeeting for Windows, Gnome-meeting for Unix, and OpenPhone.

Overall, Linphone is an excellent option for those looking for a reliable web phone with a wide range of features and compatibility with various SIP implementations.