Chinese company Huawei is offering the UK £50m to put a mobile network on the underground in time for the 2012 London Olympics, according to The Sunday Times.
The offer is a gift from one Olympic host nation to another, the report said.
The deal would see Huawei install mobile transmitters along the ceilings of tunnels so commuters can make and receive calls on the tube.
In November last year, Mobile reported that operators were close to signing a £150m investment deal to build a mobile network on the Underground.
The deal between Transport for London (TfL) and the big four operators has received backing from the Mayor of London as long as there is no cost to the taxpayer.
The deal was at risk of delays after a stand off between the operators and the French company TfL favours to run the managed services part of deal, Thales, over commercials. Mobile also revealed last year that Huawei had been lined up to manage the equipment as part as a services contract.
The deal is expected to be signed by April. It is likely to be limited to the Central, Jubilee and parts of the Piccadilly line until after 2012.