If you enter the wrong PIN three times, your SIM card will become locked. You'll need a ‘PUK code’ to unlock the SIM - call us on 333 free from a Three phone or 0843 373 3333 from any other phone (5p per minute from a BT landline, other networks may vary).
You'll be asked to enter a PUK code every time you plug your dongle into your computer until you enter it correctly.
To enter a PUK code: