Why do I need a 4 digit telephone PIN and how do I set it up?

Setting a 4 digit Telephone PIN that’s known only to you is one way you can protect your service against unauthorised access and changes. It’s also the quickest and easiest way for us to identify you as we’ll ask for it each time you call.

You can set and change your Telephone PIN in the account details section under Manage Account in your online account. Make sure the PIN cannot be easily linked to you or guessed by a third party.

Read here about other ways you can protect your account.