Coverage will be available for O2 customers in five stations in Glasgow
Passengers on Glasgow's Subway network are now able to use their mobile phones underground.
Coverage is available for O2 customers in five of the busiest stations - Buchanan Street, St Enoch, Hillhead, Partick and Govan.
Coverage will initially be limited to stations and platforms, but it could be extended through the tunnels if there is enough interest from customers.
It is hoped the coverage will improve communication and passengers' safety.
Gregor Borrie from O2 said: "From today, passengers will be able to walk into the five underground stations, make voice calls, send messages, send photographs and browse the internet over their phones
"It's pretty much exactly what they can do whilst over ground, it's much the same service across the five stations."