@13shej
Welcome to this user forum for BT Retail phone and broadband customers.
This relates to dialling 1471 to get the last number called.
If you choose the option to call the number that is read out to you, then you will be charged 35p plus the cost of the call.
If you simply make a note of the number, then hang up and redial, then you would pay the normal rate for the call.
https://www.bt.com/help/landline/all-about-bt-1471
