Operators in Oceania, Eastern, Southern Asia to drive global CAGR of 59%, predicts Ovum.

Global VoLTE connections will grow to 3.33 billion by 2021 from 324 million, predicted Ovum on Friday.

That forecast represents 53% of expected worldwide mobile subscriptions by 2021.

"The main reason operators are strengthening their commitment to roll out VoLTE today is for cost reduction," explained Craig Skinner, principal analyst at Ovum, in a research note. "The better spectral efficiency of moving voice to VoLTE allows spectrum to be re-purposed for mobile broadband. Longer-term there is the potential to shut down legacy 2G/3G networks and simplify the network."

Operators have also been encouraged by the growing number of VoLTE-capable devices and successful service launches by competitors, Ovum said.

"Although there are direct benefits from VoLTE to end users in terms of call-setup times, simultaneous voice and data sessions, and improved voice quality, it is operators rather than consumers that are driving VoLTE uptake," said Ovum senior analyst Paul Lambert.

"In the future, operators will be able to use VoLTE to offer new services, or enhance existing services with new features," he added.

North America boasts the lion’s share of VoLTE connections today, but Ovum expects Oceania, Eastern and Southern Asia will be the biggest VoLTE region in 2021.

"North America and the more developed countries within Asia and Western Europe will see close to or all LTE subscriptions being VoLTE-enabled by 2021," Skinner said. "This will drive uptake over the [forecast] period at a CAGR of 59%."

By the end of 2021, the countries with the highest number of VoLTE connections are expected to be China, with 1.08 billion; the U.S., with 379 million; and Japan, with 147 million. VoLTE penetration in advanced markets like South Korea, Japan is expected to reach 99.4% and 96.7% respectively, while Norway will sit third with a penetration rate of 94.1%