Mumble is a program frequently used for voice communication in Lojbanistan. It is free software that runs on Android, Windows, OS X, Linux and provides encryption and good sound quality. To get started, install the Mumble client and connect to a server listed below.
Start from the first server. If you can see it's not used try the next ones.
It is a good idea to announce your presence on Mumble to the community, e.g. on Lojban IRC or other Lojbanic Forums, either in advance or when you're ready to start chatting. In fact, some lessons can be given by means of Mumble, inquire in #ckule to get in on them.
Whenever two or more people are unmuted, a bot records all activity in the alga room on the zbaga server. The recordings can be listened to here. To talk without being recorded, you can create your own room, or if moving everyone is impractical, you can send "vreji: ko na jundi" to stop it from recording and "vreji: ko zmiku" to have it resume.