You may not be well-familiar with Rebtel, but the company is currently the largest independent mobile VoIP provider now that Skype is under the Microsoft umbrella. Rebtel, which routes international calls made from mobile phones and landlines to local numbers (specifically to minimize the cost of calling abroad), counts more than 13 million connected users and offers its services in more than 200 countries around the globe. (Not to mention an expected run-rate of $75 million by December of this year — and profitability since 2010.)

Full Story: Chasing Skype: Rebtel Looks To Put An End To Dropped Calls With New iPhone App