T-Mobile rumoured to have increased UK interworking SMS charges to 4p

I had this anonymous tip / rumour sent in last night:

T-Mobile UK have just increased their interworking charges (the rate other networks pay them for terminating SMS) from 3p to 4p. All the other UK networks are 3p. Expect SMS aggregators all over the land to start putting their prices up across the board, as most of them can’t distinguish traffic between one network and another so will have to do the whole lot rather than risk losing money. Might even see the cross-network rates rise on other networks mobile price plans, who knows..

I haven’t had the opportunity to verify this. I phoned T-Mobile’s UK press office to confrm this, but, alas, got voicemail a few times.

Can anyone confirm this?

Update @3pm: A few people in the know reckon that T-Mobile would need their heads looked at if they did this. However no confirmation as yet so treat with a big pinch of salt.