Customers will be able to make calls and go online anywhere on the London Underground by the mid-2020s.
Transport for London (TfL) has announced plans to have 4 G coverage throughout the Tube network for mobile users.
The Jubilee Line will be the first to benefit from getting full connectivity from March on both platforms and tunnels.
The London Underground and TfL rail services already have 260 wi-fi-enabled stations.
“We have begun the complex work to allow our customers to be able to get phone reception within our tunnels from March 2020, with more stations and lines coming online during the coming years.” Shashi Verma, chief technology officer at TfL, said.
While London Mayor Sadiq Khan: “This is a significant step for the millions of people who use the Tube each year.
“Introducing 4G and, in the future, 5G will help Londoners and visitors keep in touch and get the latest travel information while on the go.”
The Jubilee Line trial section will include ticket halls and corridors from Westminster to Canning Town-excluding London Bridge and Waterloo stations.
The stations in London Bridge and Waterloo are scheduled to be ultimately 4 G later, subject to final approval, TfL said.
The entire project is projected to require 2,000 km (1,242 miles) of cabling. Engineers are working weekend shifts to minimise disruptions.
The commuter ritual of frantically firing off emails using station Wi-Fi before hurtling back into the no-signal blackness of the Tube’s tunnels will soon be no more. The London Underground has mobile coverage of 2 G, 3 G and 4 G on its platform.