The police are to get full Airwave digital radio coverage on the London Underground network from next spring.
They will be able to use their radios at all London Underground stations once network upgrades and testing are completed by the end of March.
Police minister Vernon Coaker said, "The testing and release for operational use at all underground stations is due to be completed by 30 March 2009."
Improved radio contact when underground was demanded by police in the wake of the 7 July 2005 London Underground bombings.
Airwave is being used by all the emergency services overground.