Lost and stolen mobile phones cost users thousands of pounds each year.

And there has been no way of stopping a phone from being used by an unauthorised person.

Now a biometric technology which safeguards access to handsets using voice authentication has just been announced by SchlumbergerSema and their business partners, UK voice and signal specialist, Domain Dynamics.

Unlike previous, unsuccessful attempts at this application, the security system runs on a standard SIM (subscriber identity module) card and requires no additional hardware, making it cost-effective and simple to introduce.

Current technology uses a locking mechanism, which operates through a PIN (personal identification number)

code to ensure only legitimate users can access a phone. If you have the PIN number, the phone assumes you are its rightful owner/operator.

The new system is rather different. Although a PIN number is still required, authentication also requires the user to speak a phrase or word as the phone is switched on. This word or phrase is compared in real time with a reference voiceprint stored inside the tamper-proof SIM card's memory.

If the voice print does not match the stored data, the phone refuses to work.

This system provides an ideal solution to the problem of mobile handset and calls theft and serves as a secure safeguard for industry advancements.

Premium charges involving internet commerce could soon be up to 100 times the present rates and higher bandwidths start to allow mobile phones to be used for mobile commerce and confidential transactions.

So the potential loss from a stolen handset could rise astronomically. The mobile phone industry has been concerned for some time about misuse of these new tariffs but the new security system could provide a workable answer.

Jorgen Rasmussen, of SchlumbergerSema, said:

"Voice authentication is the most natural method of introducing state-of-the-art security into the mobile phone marketplace.

"By basing the solution on the standardised SIM platform, it becomes cost-effective and simple, providing a highly-flexible mechanism for operators to address the widespread public concern over privacy and security."

His company provides the SIM ToolKit applet, Domain Dynamics provides the voice authentication algorithm, and Mitsubishi Electric Telecom, has implemented the technology on its Trium Mondo GSM/GPRS PDA phone.

An impressive team - but have they got it right?

The new system is provided as a 2.5 Kb applet, which can be loaded on to any standard SIM card.

A tiny amount of memory usage includes everything needed for voice authentication, from the process which lets a user enter his or her voiceprint by repeating chosen word or phrase three times to the sign-on and comparison procedure for daily use.

This is a brilliant concept and hopefully one that will change the way we look at mobile phone security and stem the theft of 700,000 phones a year.

The communications industry is ripe for new ideas and secure commerce could well provide the revenue stream to fund some much needed development.