What are some alternatives to Skype and Vonage on Ubuntu

[unbuntu77]

if all you want to do is make video calls with people you know in the USA, then I'd expect Google Voice / G+ hangouts to have everything you need. they're both FREE. Just verify your account with an already existing phone number and you're all set. Skype is fair priced but I personally think its overly prone to crashes and other problems. (mobile versions of it, anyways).

http://getapps.cc/what-are-the-best-skype-alternatives/

[MissMonicaE]

I use Jitsi--it's a client, but they'll also give you a free XMPP account if you want one. It works for AIM, Facebook Chat, Google Talk, ICQ, Ippi, Iptel.org, MSN, SIP, and Yahoo accounts as well as XMPP, which is handy. Also it comes with crypto out of the box!
ETA: Also, unlike Skype, you can video conference for free.

[Paddy Landau]

I use Jitsi … Also, unlike Skype, you can video conference for free.

And, presumably, unlike Skype it has no backdoor mandated by the USA government.

[Linuxratty]

WebRTC...The version of Fire Fox you got this morning, well it's available to you right now.
The down side is it only works for two people.

"Following the recent introduction of full Web Real-Time Communications to Chrome, Tuesday's update to Firefox makes it the second browser to support the plugin-free protocol.

The debut of WebRTC, as the protocol is known, in Firefox 22 (download for Windows | Mac | Linux) is no small potatoes. "Plugins are the single largest source of security and stability issues that we see," said Johnathan Nightingale, Mozilla's vice-president of engineering for Firefox.

WebRTC is planned for Firefox for Android (download), which also updated Tuesday, but it has yet to be added to the mobile browser.

On the surface, WebRTC sounds a lot like Skype. It lets you conduct voice and video calling one browser to another via its PeerConnection component, but it also lets you transfer data directly between two browsers thanks to a component called DataChannels. These were both added in Tuesday's new version of Firefox stable."

http://news.cnet.com/8301-1001_3-575...s-full-webrtc/