FriendCaller Shows There Is Voice Beyond Skype

FriendCaller, a browser-based click-to-call voice calling service developed by the Dortmund, Germany-based startup C2Call, is once again showing that despite Skype’s monstrous market share, the game isn’t over just yet. The company is adding over 15,000 new users every day. In past three months, it’s added a million new subscribers for a total of 1.4 million to date. So far, these folks are making about 250,000 calls a day.

FriendCaller is a simple and barebones free phone service, and in that lies its beauty. In order to make phone calls, you don’t need any special software: A 750-kilobyte, Java-based (s orcl) soft client downloads and loads up inside a web browser. You can sign in using Facebook, but it’s not necessary. FriendCaller gives you a special link (CallMe links) to share via social networks, email and instant message. Your friends can click and call you, and they don’t need to register with the service.  In addition, the company has special FriendCaller apps for the iPad, iPhone, iPod touch (s AAPL), Android (s GOOG) and Facebook.

If you wish to make phone calls to external phones outside the C2Call’s footprint, you need to sign-up for an account and pay for the calls; from the U.S., it costs about 2 cents a minute to 35 different countries. From April 2010 to early August 2010, the two-year-old C2Call had generated $2 million in revenues, showing signs that it has a business model, as long it keeps adding people and encourages them to keep talking.

CEO Martin Feuerhahn and CTO Michael Knecht started C2Call in 2008. The service is based on internally developed technology and is hosted entirely on Amazon’s (s AMZN) cloud. It scales on an as-needed basis. FriendCaller’s early success has helped the company raise $2 million in Series A funding from original Skype investor Bill Draper of Draper Investment Company, High-Tech Gründerfonds and Klaus Wecken, co-founder of KHK Software.

Try this one out — it might pleasantly surprise you!

Updated: As per your requests, here are some more technical details from folks at C2Call:

Is the Java client open source?

No, the Java client is our own proprietary development, but we are using open standard protocols like SIP/SDP/RTP to establish a connection between the clients.

Is the protocol for phone calls open or closed? What is the protocol?

[It’s] an open protocol SIP (Session Instantiation Protocol). We can connect to our own service, but we also have a client for third-party SIP providers. Very soon, we will also open up our network for 3rd party SIP devices like SIP soft phones or SIP-enabled mobile devices (e.g. Nokia mobile phones, with built-in SIP client)

How does the service work? Is it based on peer-to-peer topology?

It establishes a platform-independent, peer-to-peer connection through any Java-enabled Internet browser. We host a SIP-compliant backend infrastructure with SIP proxy, media relay, presences service, etc. However, the actual audio connection on VoIP calls will be peer-to-peer whenever possible, which sometimes depends on the firewall/NAT. As fall back, we can always use the media relay, hosted in our back-end system.

What codec do you use?
We use iLBC, Speex, uLaw, aLaw, GSM codecs