Facebook recently added a video calling chat function that allows members to converse with their friends on the social network using VoIP technology powered by Skype. However, if you're not a member of the social network, don't panic, here's three other free VoIP clients and a couple of Skype add-on that we love.

TeamSpeak 3.0.0 RC1 (32-bit)

TeamSpeak is a VoIP tool that allows many users to chat over the internet: team-mates playing their favourite games, businesses holding conferences, or just friends and family catching up with the latest news - it could be used by anyone.

You may need to spend some time setting TeamSpeak up, though, because it's not just about two-way chat: given the right hardware, the program can handle thousands of simultaneous connections. To make this work requires both server and client components. The server hosts the connections (you can create your own, or maybe make use of someone else's), and the client, this package, carries out the chat.

Skype for Windows

Skype 5.5 is the latest release of the popular VoIP, instant messaging and chat tool.

A major addition in this version is the new Facebook tab, which provides easy access to your Facebook news stream. You can check what's going on with your friends, add comments and update your own status, all within Skype. And another click gives access to your phonebook, from where you can text or call your Facebook friends (free of charge, if they're also Skype users, potentially a real money-saver).

Skype Voice Changer 1.0

And now you've got Skype, why not get Skype Voice Changer. As the name suggests, the application makes it possible to change the sound of your voice during Skype conversations by applying a number of effects to it.

MP3 Skype Recorder 1.10.1

Skype is also perfect for recording any voice calls you make – perhaps you’re interviewing someone over the phone or want to record a call so you can jot down notes later. Visit the Extras section of the Skype website and you’ll discover a number of options for recording your Skype voice conversations. Unfortunately, they all cost money. Some, like Pamela Basic do exist in cut-down form, offering to record up to 15 minutes of conversation at a time, and while you can get around this limitation by simply recording your conversation in 15-minute chunks, it can be a little fiddly to do and relies on you keeping one eye on the clock as you chat.

MP3 Skype Recorder is a completely free alternative that offers no arbitrary recording limits, and like its more expensive brethren is relatively easy to set up. Make sure you have a version of Skype with the Extras Manager installed (visit the Extras Shop and download the version of Skype listed here if you discover the Extras option is greyed out in Skype’s Tools menu).

iCall Free VoIP 1.3.1

Most iPhone users can take advantage of tariffs that include a certain number of free call minutes each month, but after this allowance has been used up, it is a matter of paying by the minute to speak to your contacts. iCall Free VoIP, as the name would suggest, enables you to make even more free calls - even from an iPod or iPad.

The app can be used over a 3G or wifi connection. However, at the moment the app only offers free ad-supported calls to the US and Canada from within these countries - hopeful would-be-users in other countries will have to wait for better international support.