100M Mobile VoIP Users by 2012 = a Fat & Happy Skype

As my readers well know, I’ve long been a champion of mobile VoIP services, from Gizmo to Truphone to Nimbuz to Skype. I’ve used and at some point, liked them all, though lately I’m fixated on Skype, mostly because of how simply it works. I think it will be one of the winners of the mobile VoIP sweepstakes, a market expected to grow to 100 million users by 2012, according to Juniper Research.

According to a report released by the UK firm today titled “Mobile Voice Strategies: mVoIP Opportunities & Business Models,” a large portion of mobile VoIP traffic is going to run over Wi-Fi networks, thus diminishing the circuit switch market. It estimates that by 2015, VoIP traffic over Wi-Fi will account for about $5 billion in revenues.

As mobile VoIP continues to gain momentum, I expect to see phone companies — which have been fighting the mobile VoIP wave tooth and nail — start buying up startups in the space, many of which have built products that go beyond plain-vanilla calling plans. Nimbuzz, Truphone, iSkoot and others are all ripe for acquisition by the likes of major international mobile players. As to potential buyers, I think Vodafone (s vod), T-Mobile and AT&T (s t) will be among the first looking to cash in on the action.