I have just bought a SIM only contract for my wife, and now intend to transfer my own mobile account to BT. When you go through the purchase options for the new SIM, you confirm you have a broadband account and then there are only 2 options coming up - change the SIM contract that my wife has, or upgrade it to 5G, neither of which I want. It doesn't seem to be possible to add in a new mobile number and get a SIM for it.
