The Voice-over-LTE (VoLTE) market is expected to grow at an annual rate of 47.46 percent through 2021, driven in part by a rapid increase in shipments of LTE-enabled devices, a new report from Research and Markets finds.

The number of LTE devices shipped doubled between 2014 and 2015, from about 450 million units to around 900 million units, according to the firm. China had the highest growth rate, jumping from 90 million LTE device units shipped in 2014 to about 300 million units in 2016.

The firm anticipates that LTE-enabled devices will account for about 50 percent of all smartphone shipments in 2017. That figure is expected to grow to more than 72 percent by 2020.

“The access to a wide range of handsets influences subscribers to choose to reject different wireless communication technologies,” a Research and Markets analyst commented. “The simplicity of VoLTE architecture ensures several operational benefits to the network operators and also ensures cost-effectiveness. VoLTE networks allow voice and data on the same network, eliminating the need for separate networks.”

The proliferation of LTE-enabled devices mirrors a forecasted uptick in VoLTE subscriptions.

Ericsson’s Mobility report earlier this year forecasted the uptake of VoLTE to accelerate, estimating subscriptions would hit 3.3 billion and account for 60 percent of all global LTE subscriptions by the end of 2022.

Research and Markets recognized companies including AT&T, Ericsson, Nokia, SK Telecom, and T-Mobile as key players in the global VoLTE market.

Research and Markets’ full report can be found here.