Via Spare Room, it has been revealed that you can listen in to details on an 021 (Vodafone) phone number, change plans, buy SupaPrepay addons and more all by knowing the 021 phone number.

This comes a couple of months after the Telecom security scare, where you could change your Telecom mobile to any number to intercept texts, send texts or call using another persons account.

• See how the loophole works here