Legacy, circuit-switched mobile voice networks could eventually disappear if Voice over LTE (VoLTE) continues its momentum.
A recently published report from Signals and Systems Telecom (SNS Research) says VoLTE service revenue will grow at a Compound Annual Growth Rate (CAGR) of 36% between 2015 and 2020.
CAGRs are mean growth rates over a specified period of time longer than one year.
And the report says that VoLTE services will account for nearly $120 billion in annual service revenue by 2020.
Global mobile service revenue is projected to be $1.137 billion in 2015, according to numbers published by statistics portal Statista.
AT&T, T-Mobile, and Verizon are among the Mobile Network Operators (MNOs) that are actively launching networks using the data architecture, LTE-based voice tech in the U.S.
VoLTE places voice calls over an IP-based LTE data network—the same kind of network used for mobile Internet data sessions—rather than traditional circuit-switched networks.
Circuit-switched networks are the type of traditional telephony communications where a point-to-point channel or circuit is established for the transmission of a call. They're considered inefficient because they require dedicated physical connections to be opened for the duration of the call.
Traditional, and inefficient, 2G and 3G networks using circuits will likely be retired ultimately, to free-up spectrum.
Voice over LTE
VoLTE uses packets to carry the voice call. In other words, the voice service is carried over an IP Internet connection, just like a broadband Internet session.
Significant capacity gains are realized over classic circuit-switching, in part because a dedicated connection doesn't have to be allocated to one call.
The IP Multimedia Subsystem (IMS) architecture that VoLTE is based on also allows MNOs to offer better-quality HD voice telephony.
Commitment to VoLTE
"VoLTE is beginning to gain momentum globally," SNS Research says in its report.
It says it has found that mobile operators remain committed to VoLTE as "the long-term solution to secure a fully native IP-based telephony experience."
And that "nearly all VoLTE operators are committed to migrate existing mobile voice subscribers to LTE in order to re-farm their 2G and 3G spectrum."
Half of smartphones to be VoLTE
SNS thinks that VoLTE-capable smartphone shipments will "grow at a CAGR of 33% between 2015 and 2020, eventually accounting for over 950 million unit shipments by the end of 2020."
The total global smartphone shipment forecast worldwide stands at 1.4 billion units in 2015 and 1.9 billion units in 2019, according to statistics portal Statista.
Based on those numbers, half of all smartphone shipments will be VoLTE-compatible by around the end of the decade.
Current VoLTE-capable smartphones include the Apple iPhone 6 and some Samsung Galaxy S6 phones, for example.
In addition to the simple bandwidth and efficiency gains of VoLTE over traditional circuits, the switching-off of older 2G and 3G networks, and the re-farming of that bandwidth, is attractive to MNOs. It will, in part, drive VoLTE adoption.
The advantages are that MNOs get to use the frequencies more efficiently, operate more phone calls, and push more data in the same space.
VoLTE was first deployed by South Korean operators in 2012.
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