A revolutionary automated system that roots out accidental 999 calls has saved the Metropolitan Police �23,600 and hundreds of working days since its introduction in July.

Accidental emergency calls are a big problem and put a huge strain on the services.

Many are made from mobile phones because under an EU directive the nine key on the keypad cannot be locked and can be easily pressed when in a bag or pocket.

Last year accidental 999 calls from mobiles increased by more than 75%, with 30,000 made in two months alone, police said.

Detection

Any 999 calls identified by an emergency operator as silent are now put through to the system which plays a recorded message telling the caller they have reached Scotland Yard.

The caller is instructed to press five on their keypad twice if they need an emergency service, otherwise the auto attendant informs the exchange that no one can be heard and the line is made free.

The system only applies to silent calls. If any noise is detected callers are put through to the priority service and all calls are recorded.

It was developed in conjunction with telecommunications firm Ericsson and introduced at New Scotland Yard.

Global interest

The Commissioner of the Metropolitan Police Service, Sir John Stevens, said: "Accidental calls from mobiles were putting a great strain on our 999 service and I am justifiably proud that the Met has led the way in developing a solution to this problem.

"Met Operators can now concentrate on genuine emergency calls, offering an even faster response time to people in distress.

"As well as providing considerable savings to the Met it improves our overall delivery of service to the public."

The success of the 'auto attendant' has gained interest from police forces across the world, including the United States of America, Canada and New Zealand.