JVoIP is a Java VoIP SDK for developers to easily build SIP client applications or add VoIP call capabilities into any Java application. The whole library consist of a single 1 MB .jar file implementing a full features SIP client including SIP and media, mute, hold, transfer, forward, conference), DTMF, IM and many others with a wide range if codec's included (G.711, G.729, GSM, iLBC, SPEEX, OPUS).