British mobile network operator (MNO) O2 UK has announced the commercial launch of its ‘Wifi Calling’ and ‘4G Calling’ services. In a press release the cellco said that its Wi-Fi-based calling solution will enable customers to send and receive calls using the wireless technology even when they were unable to connect to its cellular network. Meanwhile, O2 UK’s 4G Calling service – which uses voice-over-LTE (VoLTE) technology – will reportedly provide its subscribers with ‘clearer calls and better indoor coverage over [its] fast 4G network’. At launch, both services will initially only be available to those customers with the iPhone 7 or 7 Plus handsets who are signed up to O2’s consumer post-paid, SIM-only and business tariffs; the operator says it expects to expand connectivity to other handsets ‘soon’. Meanwhile, although Wifi Calling will be available ‘wherever there’s Wi-Fi coverage’, O2 has confirmed that 4G Calling is initially only on offer in London, Leeds and Slough, with more cities to be added to the coverage area over the coming months.