NTT DoCoMo, AT&T set for VoLTE launch

The long-wait for commercial voice over LTE services could be coming to an end as a pair of substantial carriers announced plans to launch VoLTE services in the coming months.
Japan’s NTT DoCoMo reported yesterday that beginning in late June its “extra-high speed” XiTM service will offer VoLTE voice and video calls. The service will allow customers to conduct VoLTE calls while at the same time transmitting traditional data over the LTE network. DoCoMo will provide free access to the VoLTE video calls through the end of August, at which point customers will be billed both voice and data charges for using the VoLTE service.
Initial device support will include four smartphones and a pair of tablets set to launch in the coming months. The devices will require a software update to enable the VoLTE offering.
Domestically, AT&T said it plans to launch High Definition Voice services running across a VoLTE service in select markets across portions of Illinois, Indiana, Minnesota and Wisconsin. The carrier said the service will provide for clearer voice calls while at the same time enabling customers to access LTE data services.
Initial support for the service will come from Samsung’s Galaxy S4 Mini device.
The move to VoLTE will allow wireless carriers to transmit voice traffic more efficiently and eventually shutter legacy 2G and 3G networks that are currently burdened with carrying all voice traffic and a good portion of data traffic. Analysts noted in an RCR Wireless News report last year that carriers could see carriers achieve up to 40% more spectral efficiency running voice traffic over their LTE networks compared with legacy systems.
Comments in that report also noted that carriers with legacy GSM-based networks – like AT&T Mobility and NTT DoCoMo – would be able to rollout VoLTE services on a market-by-market basis due to the backward compatibility between those 2G/3G and LTE networks, while operators using CDMA to power their legacy systems – Verizon Wireless – would likely need to launch VoLTE services network wide in order to ensure that customers would not see a degradation in service quality should they need to switch between technologies. Verizon Wireless earlier this year seemed to push back its planned launch of VoLTE until later this year. The carrier has nearly reached LTE coverage parity with its legacy CDMA network.
Sprint, also a legacy CDMA-based operators moving to LTE, announced last month plans to launch HD Voice services by mid-year, though has yet to announce plans for VoLTE. The carrier earlier this year seemed to emphasis plans to launch voice over Wi-Fi services over a VoLTE solution.
T-Mobile US for its part has offered HD Voice service over its HSPA-based network since early last year. MetroPCS, which T-Mobile US acquired last year, rolled out VoLTE services across portions of its network in 2012, however further expansion of that offering has been put aside as its operations have been integrated.
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