If you think open source VoIP platforms are for tiny little startups that trade scalability and reliability for reduced capex, you should know that German service providers carry nearly 2 billion minutes of commercial VoIP each month over open source platforms. There can’t be a stronger validation of open source VoIP platforms than this.
So who are the heroes? 1&1 and Freenet lead the pack. 1&1 serves 1.76 million VoIP subscribers on OpenSER – making it the largest VoIP offering based on open source platform - while Freenet serves around 0.8m on SER. Together they ship over 1.5 billion minutes per month on these modest-but-robust platforms.
One small step for open source. One giant leap for VoIP. I bet you would develop a crush on this open source stuff if I told you how many of these VoIP lines in Germany are primary phone lines. Unfortunately I don’t have that info yet.
OpenSER is a fundamental building block of 1&1’s distributed VoIP architecture, and is used for functions like registration of phones, routing of calls, and other subscriber features. The service provider has obviously added extensions of its own. Along with OpenSER, 1&1 also uses modules from other open source platforms like Asterisk and Callweaver. UK’s Truphone also uses a mix of OpenSER and Asterisk.
OpenSER, based on SIP, was developed in Germany. The project has 20 full-time developers and over 150 regular contributors. In fact SIP itself has roots in Germany (Technical University of Berlin).
