Mobile phone users are being warned to personalise their answering service PIN numbers, after the greeting on a York woman's phone was replaced with an offensive message.

Tracy Arthur, of Westfield Place, Acomb, bought her BT Cellnet mobile phone in October last year, but did not set up the answering service until recently.

When she got her husband, Nigel, to test it, the usual "Welcome to BT Cellnet," had been changed to, "I'm a paedophile. I'm coming to get you."

Tracy said: "I was really upset. My phone is with me 24-hours a day, and if it isn't with me it's locked up where nobody could get hold of it.

"I only really got the phone to use in an emergency and the only people who ring me on it are my husband, my friend and my daughter's school.

"I was worried that my daughter's school might have tried to phone me and heard that message, that's what upset me most." A BT Cellnet spokeswoman said it was important that all new users changed their answering service PIN number at the earliest opportunity, or it would be possible for other people to access their messages and change their greeting.

She said: "The PIN code for all pre-paid phones is set at the same number. When you set up the voicemail it does ask that you change the code for security reasons."

The spokeswoman said anyone could call a mobile phone number and, if the owner had not personalised the voicemail PIN, they could get through to the option allowing them to change the greeting.

She said: "This was a particularly bizarre message, but I've never dealt with a complaint saying that someone has recorded a voicemail message like this before."

Mrs Arthur received a £20 call voucher to compensate for her inconvenience and her calls to BT Cellnet about the problem.

She said: "I think there should be a warning on the box when you buy your mobile phone."

Updated: 10:30 Friday, January 26, 2001