When Matthew and Angela Sima bought their middle-schooler her first cellphone, it came with a wake-up call. A stranger started sending their little girl unsolicited text messages.

So, the Jupiter couple took a proactive step: they turned to parent monitoring software to track their daughter's cellphone activity. Just like computer monitoring software, which became all the rage once the personal computer proliferated in American homes, cellphone monitoring software for parents is growing in popularity in a world where the average teenager has a cellphone within reach 24/7.

Using My Mobile Watchdog in the three years since, the Simas can not only monitor the texts, emails and photos sent or received, the applications downloaded and Internet searches performed on their daughter's phone, but they can block applications and control the times she uses the phone. Even better, the Simas said, they get instantaneous alerts whenever contact is made by or to a phone number not on a pre-approved list.

"There's no such thing as privacy in our family," Angela Sima told her daughter when she objected to the extra set of eyes. "Our job is to protect her."

A 2010 Pew Research Center study found that 75 percent of 12- to 17-year-olds have cellphones — up from 45 percent in 2004. More of these devices are smart phones, the high-tech variety with Internet access, media players and the amplified cyber-dangers that come with them.

"Kids didn't used to have smart phones. Now, they want a smart phone more than a laptop [computer] or a bike," said Robert Lotter, CEO of eAgency Mobile Security, the makers of My Mobile Watchdog. "The smart phone market has increased the threat [to children] dramatically, so there is definitely an uptrend" in parents' buying monitoring control products.

In a July 2011 study, the Family Online Safety Institute found that 25 percent of the parents surveyed used parental controls to monitor their kids' cellphone use; 44 percent restricted kids' ability to download games and applications; and 70 percent checked their kids' cellphone for sent and received text messages.

"Our kids are vulnerable. That's why we protect them," said Greg Schiller, a Special Victims Unit prosecutor for the Palm Beach County Sexual Predator Enforcement Program. "This kind of software allows parents to be there and make sure no one is taking advantage of their child."

The idea, too, is to protect kids from themselves.

"You hear so many stories about kids going off with the wrong crowd, or sending inappropriate pictures back and forth," said Mae Belgrave, 33, a Boca Raton software developer and mother of three. "You think you know your kids, but they're like totally different people when they're around their friends. So, you just worry about them, and the cellphone gives them so much freedom these days."

Her 12-year-old's phone has Mobile Spy, which allows Belgrave to keep up with her texts, phone calls and — thanks to a GPS tracker — movements.

"That's a wonderful feature, to be able to check to see she went where she said she was going to," said Belgrave, who is even more confident in her daughter's trustworthiness after a year of seeing nothing amiss via Mobile Spy. "She's responsible. We just wanted to take that extra precaution."

Plenty of competitors

Detective Rich Wistocki handles Internet crimes against children for a suburban Chicago police department and, as a private consultant, travels the country speaking to parents about how to avoid cyber-dangers. Topping his list of recommendations is My Mobile Watchdog, which is used not just by parents but by law enforcement agencies that have found it vital in tracking down predators and drug dealers.

Wistocki credits the product with helping his department capture about 15 sexual predators and 50 drug dealers in the past three years.

"My Mobile Watchdog allows parents to be in their child's life," he said. "Other companies say they do what [My Mobile Watchdog] does, but I haven't seen it."

But there are plenty of competitors, mostly spyware companies such as Mobile Spy. Whether one is better than the other is up for the consumer's interpretation, but there's no question they offer different products.

One of the biggest differences is in the spying. Spyware can be installed on anyone's phone — a child's, a spouse's, an employee's — without their knowing. My Mobile Watchdog is only for parental monitoring of kids' phones, and a periodic notification is sent to the kids' devices telling them they're being monitored.

Lotter said the difference is intentional, because he has a moral objection to spying on anyone, even children.

While some people may think such extensive monitoring sounds intrusive, experts say it's a responsible, and legally viable, means of keeping close watch over kids, whether parents tell them or not.

"One hundred percent," said David Seltzer, a former cyber-crimes prosecutor and now a cyber-crimes defense lawyer in Miami. "I recommend it to all my clients."

Stealth monitoring of such activity may be a technical violation of Florida's wiretapping statute, Seltzer said, but it's not prosecuted in such instances.

"Unless the child is an emancipated adult, you can monitor their activity" on the cellphone without their knowing, he said. Whether parents should tell the kids they're being monitored, he added, "depends on the child."

Belgrave, though, said she and her husband opted to tell their daughter about the spyware: "If she wanted to have a phone, that was going to be how it goes."

No matter what monitoring device they use, it's critical in today's hyper-connected age that parents stay plugged in, said Mary McLaughlin, a cyber-security analyst for the Florida Department of Law Enforcement's Computer Crime Center.

"Parents need to make sure they are as involved as they can be in their child's digital life," she said. "They need to stay on top of what their child is doing."

nbrochu@tribune.com, 561-243-6603, Twitter: @nicolembrochu