Eurotunnel, the firm that operates the Channel Tunnel between the UK and France, has signed a 10-year agreement with Vodafone and EE for the mobile operators to offer 2G and 3G services within the tunnel.
Customers of both mobile operators will get access to 2G and 3G services in the North Tunnel which runs from the UK to France from March this year.
EE and Vodafone aim to offer 4G services in the tunnel at a later date.
The deal will enable the 20 million passengers that travel annually via the Channel Tunnel to use their mobile phone or tablet throughout the journey, and Eurotunnel claims that the "quality of communication will be equivalent to a call made in Paris, London or anywhere above ground".
Eurotunnel, which is based in Paris, said that it had to work with its partners to overcome a series of technical challenges in order to provide a wireless service 100 metres below sea level.
Eurotunnel has similar agreements with the French mobile operators Bouygues Telecom, Orange and SFR. The French rivals co-operated in 2012 to install 2G and 3G services in the South Running Tunnel.