AN EXPLOSION in mobile phone use has led to The Big Number Change which will mean all mobile numbers will change this month.

Twelve million phone and pager users whose numbers do not start with 07 will be hit by the change. Old numbers will fail to exist and although many users just have to add the digit 7 to the number, many numbers will change altogether. Attempts to call old numbers after April 28, will fail and the call will go through to a recorded message.

Howard Sandom, Big Number campaign manager, said: "We're all mad about our mobiles here in the UK and a new numbering system has been introduced to cope with the demand. Everybody should check their mobile numbers and those in their address books now."

The new system allows codes to be grouped into a family of easily identifiable services such as 07 for mobiles and 08 for special rate services.

To find out more about the Big Number Change call the freephone helpline on 0808 2242000 or log on to www.numberchange.org