By Amy E. Feldman

PHILADELPHIA (CBS) – Does your business do fax blasts to customers? There are things you need to know.

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Doug Walburg, owner of a company that sold directories of telephone numbers for courthouses, made sales calls to a Missouri attorney and followed up with a faxed ad. I know, you’re on the edge of your seat. But if your company sends out faxed advertisements, here is where you might want to sit up and take notice.

The lawyer who received the ad filed a class action lawsuit under the Telephone Consumer Protection Act which says it’s illegal to send unsolicited ads to any fax machine, whether business or personal, without the recipient’s prior express permission.

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You can send faxes to people with whom your company has an existing business relationship, as long as the fax number was provided voluntarily by the recipient and as long as the fax provides a way for recipients to opt-out of future faxes.

Each unsolicited fax is its own separate violation with penalties of between $500 and $1500 per fax, or a total for Mr. Walburg, of $48 million, if he loses.

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That’ll teach him not to deal with lawyers and should teach you not to send unsolicited faxes.