Best real-time communication softphone on the Linux desktop?
danielpocock.com
danielpocock.com
Server installation is deceptively easy, client installation is a bit more difficult because you must configure your audio installation. Nothing difficult for someone curious enough.
After that, all your audio communications will be a breeze. It's fast, it's low on resources, you don't even need to think about it (it doesn't hog your DSL line and when your DSL line _is_ full, you can still have some reasonable conversation), it's using Opus now so the quality is excellent, the client is available on Windows and Linux at least (I have regular conversation using these 2 OSes, no problem to report) and there are prototypes for Android, it's secure (to the extent that you must trust the server), it's multiparty, and it's Libre.
Only nitpick: it's its own standard.
Small tip: Use IPv6. If either party can not get a native connection google for a free tunnel provider. Start jitsi with -6 as parameter and it will prioritise v6 connections. This fixed all kinds of 'nat-nat-nat' setups that some friends are forced into. (Make sure the implications of having a public address are understood.)
Another wonderful thing about jitsi is the availability for multiple platforms and crypto support for otr or zrtp.