Rebtel considers itself to be one of the biggest threats to the Skype empire, so I was interested in learning from the company's CEO, Andreas Bernstrom, how they felt about Microsoft acquiring their main rival for $8.5 billion in cash. Unsurprisingly, Bernstrom said the acquisition 'validated the market' but he also had some more interesting things to say, mainly about VoIP and mobile telephony in general, and how financially sound the Rebtel business currently is.