After this week angering customers by slashing smartphone data limits, T-Mobile today backed off saying the lower limit of 500MB per month will apply only to new mobile phone customers and those who upgrade. There's still no word as to what action will be taken when those users break the 500MB cap.

Vice President of T-Mobile UK Lysa Hardy today said: “On Monday, 10th January 2011 we announced that, in line with the rest of the industry, T-Mobile would be reducing its Fair Use Policy for data usage to 500MB a month for all mobile phone customers. Following a further review of our this policy, these changes will now be introduced from 1st February, to new and upgrading customers only - not existing customers.

"There will be no change to the data packages for existing customers for the duration of their contract and we apologise for any confusion caused. The revision to the FUP is designed to ensure an improved quality of service for all mobile internet users."

The climb down follows Three's recent decision to cancel it's own data caps, after providers such as iPhone handler 02 introduced limits last year. Some analysts had speculated that the introduction of a cap may not be legal, and some T-Mobile users had expressed anger.

It's believed that T-Mobile wanted to cap users' data use partly because of the prohibitive cost of users watching video over mobile, and partly to bring the company into line with its partner Orange.

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