A new study from a London-based research firm claims that mobile voice-over-IP will become a mainstream form of communication by the end of 2012, based on rapid growth of voice-over-3G wireless users. Disruptive Analysis said its research shows mobile VoIP will eclipse fixed-mobile convergence services that use dual-mode handsets with voice-over-WiFi capabilities.

“If you take the view that operators are going to be increasingly spectrally constrained, VoIP may become more compelling because you should be able to get much higher spectral efficiency,” said Dean Bubbly, author of the report. While there are companies doing VoIP over wireless today to offer low-cost service, “the big numbers in our forecast are all carrier-based,” he added. “When they move to LTE and UMB, those are all IP networks, and if you are going to run voice, it’s VoIP by default.”

Most likely, he said, wireless carriers will begin transitioning voice traffic off their circuit-switched networks onto their 3G IP networks when it makes economic sense to do so, with spectral constraints creating some economic incentives for the move. Longer term, Bubbly added, wireless carriers will be looking to new services such as voice-integrated mashups or other opportunities.

Today, Skype, U.K.-based TruPhone and an Israeli company called Fring already offer VoIP over 3G smartphones and 3G-enabled laptops, he said, giving users the same cost advantages that VoIP service over wired broadband lines provides.

“They want 3G to compete with DSL and cable modems,” Bubbly said. “Well, you can’t say, ‘This is just like DSL, except you can’t do Skype.’ There will be phones on an increasing range of other applications--what we call non-telephony VoIP--for things like private push-to-talk or conferencing. In the consumer market, it’s quite possible to add VoIP and play a game. We also are seeing a lot of interest in VoIP mashups, where consumers do a remote log onto Facebook and upload a voice memo. VoIP can morph into things like social networking.”

The near-term opportunities will be disruptive to carrier business models, which are more likely to benefit from wireless VoIP in three to five years, when they have fully deployed IP-based 3G networks, the study concluded. Ultimately, most VoIP-over-wireless users will be using mobile carriers’ own standards-based services over 3G+ networks, Bubbly said.