AT&T's and Verizon's plan to connect their voice over LTE (VoLTE) wireless networks in 2015 is seen by some experts as a step toward widening the availability of high-quality voice while helping set the stage for future innovation in mobile unified communications.
The leading U.S. carriers said Monday that their engineers were working through a "full set of requirements, beginning with extensive testing in lab environments and then moving to field tests."
The work is expected to lay the foundation for the interoperability of other rich communication services, or RCS, like video, instant messaging and file sharing.
VoLTE is a set of specifications used to carry voice over carriers' fourth-generation Long Term Evolution (LTE) networks, which are used today for high-speed wireless data. Voice is handled separately on an older but more reliable cellular network.
Adding voice to LTE significantly improves voice quality by switching from an 8 kilobits per second codec to a newer 13 Kbps codec that uses modern compression methods. AT&T and Verizon use the latter codec, while T-Mobile has chosen a 24 Kbps codec to try to achieve a level of quality higher than its rivals'.
Potential VoLTE business benefits
Phil Marshallanalyst, Tolaga Research
Better voice quality would benefit carriers' business customers, as well as consumers. Combining voice and data networks could lead to innovations within unified communication (UC) services, Tolaga Research analyst Phil Marshall said.
"In terms of UC, we can anticipate that once stable and reliable, VoLTE will drive innovation in both the enterprise and consumer markets, and in B2B [business-to-business] and B2C [business-to-consumer] services," Marshall said.
Initially, most of the innovation will likely come from third parties providing consumer mobile apps and services like streaming video and music. These products are expected to establish the use of underlying technologies that could eventually prove useful to business, Marshall said.
"Enterprises must prepare for innovations incubated in the consumer market," he said.
The extent to which UC users will benefit from VoLTE remains to be seen. How the technology is used will depend on the deals UC vendors strike with the mobile service providers that own the infrastructure under the VoLTE service, according to Marshall, which could be a carrier or a mobile virtual network operator, or MVNO.
VoLTE advantages dependent on wireless carrier interoperability
Before VoLTE can become fully useful to businesses or consumers, interoperability will be needed across wireless service providers globally. "This is [only] a bilateral agreement between two U.S.-based mobile carriers," Michael Finneran, president of advisory firm dBrn Associates, said in an email.
Also, VoLTE service providers will have to show they can deliver video conferencing and other services that would appeal to businesses at a reasonable rate.
"Mobility is a must-have for any UC user, and that places suppliers with mobile networks in a good position, but only if they can get the rate right," Gartner analyst Steve Blood said in an email.
A more immediate problem is the technical hurdles carriers face in rolling out VoLTE. AT&T, Verizon and T-Mobile are doing a city-by-city expansion of their networks because of the limitations of LTE, Tolaga Research's Marshall said.
4G service degrades the farther a mobile device is from a carrier's cell tower, and there is no reliable way to hand the service over to a closer tower, Marshall said. As a result, VoLTE calls are often dropped.
"The change in technology means they [carriers] have to re-optimize their networks to work for LTE, and that cell boundary is certainly a challenge for them," Marshall said.
In the device market, Samsung and Motorola have released high-end smartphones that support VoLTE. The service is also supported in the Apple iPhone 6 and iPhone 6 Plus.
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