Thieves can bypass some home alarm systems by cutting the home's phone lines. But some Charlotte residents said they discovered it too late.

Bob Newman activates his security system every time he leaves his home in north Charlotte. But Newman said he learned the hard way that he and his family weren't as secure as he thought.

"I was violated in a way for 6 or 7 years thinking I was secure, that my wife was secure, to find out you're not," said Newman.

Thieves broke into the Newman's home in broad daylight last month and stole $15,000 in valuables.

Newman said the alarm company -- ADT -- never notified him because it never got a signal. The intruders circumvented the alarm by cutting the telephone line.

The same thing happened at Max Nicholson's Elizabeth neighborhood sub shop, twice.

"It's just a sinking feeling. Its awful," he said. "(I) came to work like I normally do, (I) came around the back and my back doors were just flapping around in the wind."

It's a problem Charlotte-Mecklenburg police Sgt. Jim Wilson has become familiar with.

"If they cut the phone line, there is no way the signal from the alarm can get to the monitoring center for them to call police. They have the comfort of knowing the alarm won't go off," he said.

Police said burglars spent three to four hours inside another business where phone lines were cut. They used a sledgehammer to bust through a steel safe and an ATM to steal cash.

Nicholson said his sub shop looked just as bad.

"They stole everything they could carry," he said.

In Newman's home, they picked out the expensive items including TVs, computers, jewelry and even a generator.

Reading the fine print in his ADT owner's manual, Newman now knows the company knew the vulnerabilities of phone lines.

"An intruder may cut the telephone line or defeat its operation by more sophisticated means which may be difficult to detect," said Newman.

"May be difficult to detect? But it doesn't say you can't detect it at all?" asked Bristow.

"Exactly," said Newman.

But on the ADT contract Newman signed, it states if the phone service is disconnected, an alarm signal cannot be transmitted at all.

ADT sent a letter stated their SafeWatch Cellguard Backup offers an extra layer of protection for customers in case their regular telephone service is interrupted. ADT has offered the Cellguard Backup for five years.

Nicholson and Newman installed their alarms about seven years ago, and they said it was never offered to them.

"How did you learn about the cellular system?" asked reporter Holly Bristow.

"After we got broken into," said Newman.

"Any literature? Any phone calls?" asked Bristow.

"None whatsoever," said Newman.

ADT said it regularly informs customers of new services.

Newman said let his lesson be your warning.

"If you're gong on vacation, see your security advisor and see what you got and see what can that provide you," he said. "It's going to cost you some money. But we learned the hard way, it cost us a lot more."

The people who agreed to talk to Eyewitness News for this story were ADT customers. However, Eyewitness News also spoke with customers of other alarm companies who also had their phone lines cut during burglaries.

They said they were not aware either that cellular backups were available.

After installation, cellular backup service costs about $8 more a month.