T-Mobile thinks that Vodafone's marketing of its packages with speeds of up to 7.2Mb is unrealistic.
The rival providers have clashed over the way in which deals are being advertised, with T-Mobile insisting 7.2Mb has not been reached by customers signing up.
Vodafone, reports PC Pro, says that it has been referring to "7.2Mb technology".
A Vodafone spokesperson told the magazine: "If the site wasn't busy and all the other dependables were bang on, in a test environment that's the maximum speed that technology will provide you. On average it's between 1Mb and 5Mb."
That statement was in response to T-Mobile's head of internet and entertainment Richard Warmsley's claim that: "With the [mobile broadband] dongles that are on the market today, across all the networks, to my knowledge the maximum [speed] that's been achieved is 4.5Mb."
T-Mobile was recently voted the best value UK mobile broadband provider in a YouGov survey.