EE has become the first operator in the UK to launch a fully integrated WiFi calling service allowing customers to make calls and send texts using a building's WiFi service instead of the cellular connection.
The WiFi calling offer is aimed at overcoming the problem of poor cellular coverage inside buildings, especially in rural parts of the country, and could help EE to build a competitive advantage based on the quality of its voice services.
Although other WiFi calling services are available in the UK market, EE's appears to be the first that is built on an IMS platform and does not require the use of a software app. Unlike what an EE spokesperson calls these "best-efforts" alternatives, EE's will let customers use the phone's normal dialer and address book as well as contact the emergency services.
Once the service has been activated, calls will automatically be routed over any WiFi hotspot to which the phone is connected unless the customer disables the WiFi calling service, which can be done without turning off general WiFi connectivity.
Usage will count against a customer's monthly allocation of minutes and text messages, although most of EE's service plans now come with unlimited calls and text messages.
The service essentially means EE is piggybacking on the broadband infrastructure provided by the country's fixed-line operators, but an EE spokesperson says that WiFi calling uses "negligible" amounts of network capacity and that customers paying for broadband should be able to use it however they like.
Customers of the Lumia 640, Samsung Galaxy S6 and S6 Edge handsets will be able to use the WiFi calling service beginning this week, but EE expects to add more compatible devices to its line-up over the next few weeks and reckons more than 5 million of its subscribers will be able to use the feature by the summer.
According to EE's spokesperson, newer iPhone models will support the WiFi calling service beginning later this month. The operator is also working with Taiwan's High Tech Computer Corp. (HTC) (Taiwan: 2498) on the rollout of WiFi calling.
One drawback of the WiFi calling service is that it will not support a handover to mobile if customers move out of the WiFi hotspot during a call. EE says the handover issue will be resolved with the launch of a voice-over-LTE service in the late summer.
Moreover, while EE can claim to be the only operator providing a carrier-grade WiFi calling service, its monopoly is likely to be short-lived. Rival Vodafone UK recently announced plans to launch WiFi calling as well as VoLTE this summer. (See 3 UK to Launch VoLTE by September.)
Meanwhile, Three UK -- the UK's smallest mobile network operator -- has previously told Light Reading that it expects to launch a VoLTE service between July and September. (See 3 UK to Launch VoLTE by September.)
As the name implies, VoLTE would allow operators to run voice calls over their 4G infrastructure. At the moment, voice calls made on 4G devices are sent over 2G or 3G networks using a technology called circuit-switched fallback.
Besides improving call quality and reducing set-up times, VoLTE could also help operators to overcome the problem of poor in-building coverage.
Mobile phone signals travel further and better penetrate buildings at sub-1GHz frequencies, but EE lacks any of the 900MHz spectrum originally intended to support traditional voice services and has instead been relying on 1800MHz airwaves.
It did, however, pick up 800MHz spectrum during the UK's 4G auction in early 2013 and has been running VoLTE trials over these frequencies in a rural part of Oxfordshire.
UK fixed-line incumbent BT Group plc (NYSE: BT; London: BTA) was expected to announce the launch of a WiFi calling service when it unveiled its 4G offer last month, but it made no mention of the feature. (See BT Threatens Price War With New 4G Offer.)
Currently reliant on a wholesale agreement with EE, BT expects to complete a £12.5 billion ($18.6 billion) takeover of the mobile operator by March next year. (See BT Locks Down £12.5B EE Takeover Deal.)
— Iain Morris, , News Editor, Light Reading