Linphone is an internet phone or Voice Over IP phone (VoIP). With Linphone you can communicate freely with people over the internet, with voice, video, and text instant messaging. Linphone makes use of the SIP protocol, an open standard for internet telephony. You can use Linphone with any SIP VoIP operator. A broad range of audio and video codecs are supported, including Opus, Speex and H264 (via a plug-in). Commercial support is available.