By Pat Loeb

PHILADELPHIA (CBS) — Philadelphia police and local utility companies today launched a new advertising campaign to thwart criminals who pose as utility workers to gain access to homes.

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The public service campaign, called “Be Sure Before You Open The Door,” invites residents to call 911 to get an assurance that a person knocking on their door is legit.

Officials of area utilities say they’ve tried for years to figure out how to battle the con men who try to gain entry to homes by posing as water, gas, phone, or electric workers.

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They’ve tried awareness campaigns before, but this new one has what’s been missing:  a way for homeowners to find out for sure if someone is scamming them.

“Once that call comes in to 911, the call-taker will do behind-the-scenes contacting as to whether or not a utility should be out there,” explains deputy police commissioner Kevin Bethel.   If the answer is no, he says, police will be dispatched to the home.

At today’s press conference, the new system got a big vote of approval from East Oak Lane senior citizen Sadie Williams.

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“It definitely helps me to feel safer, and I appreciate the fact that my city’s behind my safety,” she said.