Just hang up!

If someone calls claiming to be a telephone technician and asks you to press a series of buttons, hang up. Immediately!

A phone scam allows con artists to make long distance phone calls to anywhere in the world - leaving their victims with enormous bills.

Owners of business or home lines with switching - those that require you to dial nine to receive an outside line - are vulnerable to this scam. Those with only one line are not, says Bryant Steele, spokesman for AT&T.

Here's how it works: You get a call from someone claiming to work for a phone company.

The person says he wants to test your phone line and asks you to touch 9, zero, and then the pound sign - and hang up.

If you do this, you've given the person full access to your telephone line, which allows him or her to place long-distance calls that will be billed to you.

Long-distance providers have been alerted to the scam which, Mr. Steele says, has been around since the 1960s, when switches were invented.

His office has received numerous calls about it after a popular e-mail chain letter recently revived the scam.