Who, What, Why: Can phone hackers still access messages?

The News of the World phone hacking scandal has prompted an emergency debate in Parliament, but how were voicemails illicitly accessed and could it still happen?

When mobile phones were analogue, would-be snoopers could listen in using scanners. When mobile phones became digital, this option largely disappeared. But by then another way of snooping on people's private lives had presented itself - hacking into voicemail.  Mobile voicemail was introduced during the mid-1980s with users dialling a number, such as 121, to retrieve their messages. Because of poor network coverage, short battery life and people needing to listen to messages while abroad, mobile operators offered customers the chance to access messages remotely from another phone.

To do this customers would either ring their mobile number or a generic remote access number and, when they got through to a voicemail greeting, press a key such as * or # and enter a personal identification number (Pin).

For many years the mobile phones came with a default four-digit Pin such as 1234, 0000 or 3333. In theory customers were expected to change their Pin, but in practice very few people did so.

This presented tabloid journalists and private investigators with a golden opportunity. They could simply ring the number and if the caller didn't answer, enter the default Pin and access the person's messages.

"Security has been tightened but I don't think it's enough”

End Quote Carsten Maple Professor of applicable computing

Another ruse was to change the voicemail Pin from the default to prevent other journalists having access to it. Prominent hack victims were Sienna Miller, the publicist Max Clifford and Professional Footballers Association chief Gordon Taylor.