CAMPBELL, USA: Infonetics Research forecasts the number of mobile VoIP subscribers to grow from 47 million in 2010 to almost 410 million by 2015, driven by increased smartphone and mobile broadband adoption.

Diane Myers, directing analyst, VoIP and IMS, Infonetics Research, says: "The adoption of over-the-top (OTT) mobile VoIP services is growing rapidly, however, it is not without challenges. With free applications and extremely low revenue from users, it is tricky for application providers without the deep pockets of larger companies like Google, Microsoft, and Telefónica to have a sustainable long-term business model."

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"Despite the fact that we expect mobile VoIP subscribers to grow nearly 10-fold from 2010 to 2015, there is relatively little money to be made from it in the near term," Myers adds.

Infonetics in its new 'Mobile VoIP Services and Subscribers' report, finds that OTT providers, led by frontrunner Skype, dominate the worldwide mobile VoIP services market.

Co-author of the report Stéphane Téral, Infonetics Research's principal analyst for mobile infrastructure, adds: "As LTE becomes the universal mobile infrastructure, TDM voice - which is a $500 billion-a-year business - will migrate to VoLTE (native mobile VoIP)."

"In the near term, though, two key challenges need to be addressed: the world needs widely available LTE handsets that support VoLTE - and we're nowhere near that stage - and Single Radio Voice Call Continuity (SRVCC) needs to be finalized so that voice calls work seamlessly between LTE and legacy networks. Make no mistake: VoLTE is the future; it will just take many years to get there," he adds.

Native mobile VoIP will launch with Verizon's VoLTE service in 2012, however, will remain an extremely small portion of the total mobile VoIP market until there is full LTE coverage around the world, not likely until around 2020.

In 2010, operators made on average only $13.21 per user per year from mobile VoIP services, demonstrating how little revenue there is to be made from OTT mVoIP services.