Forgetting mobile numbers could become a thing of the past as an online 'phone book' allows users to text requests for mobile phone numbers.

The Mobile List provides a searchable database of members' profiles, so all you have to do is search for the name of the person you want to call. Once you have found it, you match up the profile to the person you are looking for, click on their name and the site will send a message direct to the mobile number you want, asking them to call you back.

Both searching the database and registering with it are free, but subscribers do have to input their contact information which could trigger concerns over data protection issues.

"I need to address [security]," said the site's developer Lance French. "Although I know I will not distribute this info, I need to prove it. We are only as good as our reputation."

For the list to become an effective search mechanism, all of the user's friends and colleagues would also have to submit their details to the site.

"We are looking to partner with other organisations to increase the database. We have found most members tell all their friends too," said French.

On a positive note, the service is completely free. The mobile list pays for the cost of the SMS message, a cost it foresees will be covered by its enquiry line, due to be set up imminently.

While some users will always be worried about their contact details ending up in the wrong hands, thousands of people have been happy to have their names, home addresses and phone numbers printed in paper-based phone books for years, and really this is just an online equivalent. If you want to stay ex-directory, don't register.