First of all, the Applet-phone is a SIP User-Agent with audio and text messaging capabilities. But

First of all, the Applet-phone is a SIP User-Agent with audio and text messaging capabilities. But i s also embedded in an applet where you can use it as usual if your firewall allow you to use the UDP transport. If not, you can use TCP to carry your voice in a voice messaging fashion. Your voice is recorded and encoded locally then sent as a message, decoded and played back by your peer. Voice messaging allow you to go through any firewall, so that you can continue to chat and talk with your friends from an applet !