Facebook is apparently in talks to acquire the mobile messaging phenomenon WhatsApp, reports TechCrunch.

The report did not reveal its sources, nor the potential size or nature of the takeover discussions, yet such a deal is seen as credible as Facebook seeks to bolster its mobile credentials. Neither company has commented on the report at the time of writing.

WhatsApp is available as a smartphone app in over a hundred countries and – according to TechCrunch – has a staggering 100 million daily active users globally. At the end of October 2011, the last time WhatsApp released any usage numbers, it announced that it was serving 1 billion messages per day.

As well as its scale, the fact that WhatsApp is a ‘paid for’ app without advertising is also likely to appeal to Facebook, which is under some pressure to monetise its mobile presence; the Facebook app is hugely popular, but given away for free.

WhatsApp is currently the number-two paid app in the US version of Apple’s App Store, where it sells for US$0.99. On Google Play, the app is free for the first year, and then US$0.99 per year thereafter. Data from Google Play suggests that the app has been downloaded between 100 million and 500 million times to date.

Facebook’s mobile income is currently focused on advertising. It recently noted that 14 percent of its advertising revenue (around US$150 million) in the third quarter of 2012 came from its mobile business, suggesting that its focus on mobile is paying off.

“I want to dispel this myth that Facebook can’t make money on mobile,” CEO Mark Zuckerberg told investors in October. “This may have seemed true earlier this year because we hadn’t started trying yet.”

Facebook is no stranger to making big deals. It inked a US$1 billion takeover of the mobile photo editing and sharing app company Instagram in April.