EE customers will be able to use their mobiles while trains are in tunnels as part of an upgrade of the system expected to be completed next year.
However, it remains to be seen whether callers will be able to hear over the rattle of the Subway trains’ noisy shoogle.
Glasgow Subway passengers could previously only call from their phones and use wifi for data in stations under an old system introduced in 2008 which was switched off after it became unreliable.
EE has now installed a new 4G network in the Subway’s 15 stations in time for the COP26 climate change conference, which starts on Sunday.
It said the improved 4G coverage would enable people with EE-connected phones to call, text and access data, such as for social media and apps.
The upgrade also means people will be able to continue calls and use data while walking between the street and station platforms without needing to connect to the Subway’s wifi.
This will be followed by being able to make calls from tunnels.
A spokesperson for BT-owned EE told The Scotsman: "At present, you can make calls in the stations over 4G.
“When EE has completed work in the tunnels over the coming months, you will be able to make calls there too.
"It will provide uninterrupted coverage for EE customers across the Subway.”
They further claimed: “This isn’t available in London’s Underground yet, so a first for the UK in Scotland.”
However, Transport for London said: “4G mobile coverage has been available on the eastern end of the Jubilee line since March 2020, enabling customers to make calls in tunnels.”
The spin-off for Glasgow passengers is thanks to a new emergency services network (ESN) being installed on the 124-year-old circular railway, which is the third oldest in the world after London and Budapest.
The network will be used by police, fire and rescue, and ambulance staff for calls and sending data and video.
The ESN will take priority over all other network traffic to ensure the speed of first responders receiving important data is not affected.
Valerie Davidson, acting chief executive of Strathclyde Partnership for Transport, which operates the Subway, said: “As more and more people are using a smartphone, there is, quite rightly, an increased demand and expectation for good connectivity to be available everywhere as they move about.
"The next stage will be getting 4G into our tunnels.
"When this is complete, passengers will also be able to make or accept calls when travelling with us.”
Police Scotland Chief Inspector Stevie Espie said: "The deployment of 4G coverage and ESN within the SPT Subway system is vital for the emergency services.
"ESN will allow emergency responders enhanced, priority-based access to their critical communications system, even in busier periods.”
The development comes ahead of the introduction of the Glasgow Subway’s groundbreaking new trains, which will eventually operate with no driver or other staff on board, in another British first.
They are currently expected to start service next year – two years later than planned – and initially with drivers with drivers.
However, this has yet to be confirmed following delays to the Subway’s £289 million overhaul – the biggest for 40 years.