Perhaps someone at T-Mobile has a warped sense of humour, as their announcement was prefaced with the words:
To make things clearer for our customers, we have aligned our 08 number charges with local and national calls to follow the latest Ofcom guidelines. These calls aren't included as part of your allowance in any of our price plans.
This gloss glides over the fact that they are making very substantial inflationary price increases to their charges for calling all 08 numbers.
See:-
http://www.t-mobile.co.uk/services/uk/08/I am not even sure that the prices they quote are the right way round: there are two suspicious references to off-peak charges being 6 times more than peak on one tariff, and 8 times more on another !
What a poor show all round !