VoIP client in a browser?

Google just announced that they will add support for VoIP calls in its Gmail application.

Does someone know how this will work? Did they manage to write a web-based VoIP client, or will they require the user to have Google Talk installed and somehow (how开发者_StackOverflow?) call this app from the browser?

I'd also like to provide customers with a way to make/receive calls through their browser, so that they wouldn't have to install an SIP client.

Thank you.

Google don't use a VoIP client in a browser. Instead the browser is used to initiate a callback to a phone number you must have previously registered. Once you answer that call Google Voice will then ring the destination number you specified and then bridge the calls together.

I've just noticed that in my inbox. They ask you to accept their EULA to start installing Google Voice. So it's not really a browser solution.

There are several companies that have built VoIP clients as e.g. Java applets. It is totally doable, although depending on the exact requirements it may be expensive and time consuming: for instance, echo cancellation is not exactly trivial when you need to deal with arbitrary audio drivers across any and all laptops, netbooks etc out there.

There are also consulting firms that can help with that.

Full disclaimer: I own one such company ;)