Plans to trial mobile phone use on London's tube network have been scrapped due to high costs, it has been revealed.
In March 2007, Transport for London (TfL) called for a six-month trial on the Waterloo & City line to see if it would be cost effective.
A TfL spokeswoman told silicon.com that none of the three proposals that were received were "commercially credible".
"While it is technically possible to deploy mobile-phone and data-wireless solutions on the deep-level Underground tunnels and stations, the unique nature and environment of the Tube mean that project costs would be prohibitively high at this time," she said.
TfL also said there are currently no active plans to trial or roll out mobile phone use on the tube.
Last year mobile network O2 and telecoms firm Arqiva announced they had installed radio network equipment in Glasgow's underground, which allows passengers to use their handsets during their journeys.