Bells aren't the only things ringing in school these days. Cell phones are, too.

With so many students carrying mobiles, cell-phone rules (search) are multiplying at schools across the country, but it's not as simple as turning off a ringer.

Many parents are adamant about having their children of all ages tote phones with them in case of an emergency. But educators have found the mobile devices are often used for sneaky or social reasons, not just to communicate with Mom and Dad in a pinch.

The potential for cheating, for instance, has increased with phones' text messaging and picture-taking capabilities. That's why the Salinas Union High School District (search) in Salinas, Calif., implemented a no-phones-on-campus policy.

“We don’t go around conducting searches looking for them, but if they are out and go off, they will be confiscated,” said Roger Anton, superintendent of the school district.

The rule was adopted this year after a student at the Everett Alvarez High School (search) was caught photographing an exam with a camera phone (search), apparently intending to send it to a friend.

The San Mateo Union High School District (search) doesn’t take quite as hard a line as Salinas, but this year began forbidding the use of camera phones unless an on-site administrator approves it, and allowing calls from regular mobiles only between classes.

And the Hudsonville Board of Education in the Grand Rapids, Mich., area implemented a similar cell phone plan this year, limiting use during breaks and lunch and banning cellphones with digital cameras.

Schools worry not only about cheating, but also about photos taken in locker rooms and bathrooms, disruptive classroom calls and other bad behavior. Most confiscate the devices for the day, though if there are repeat problems parent-teacher conferences are set up. Eventually kids can lose the privilege of carrying a phone all together.

Just last week, a fourth-grade teacher in Brooklyn, N.Y., got firsthand experience enforcing the public school system’s policy of no phones in class.

“It was about nine in the morning on the second day of school, and I heard a funny little computer noise,” said Michelle Wereszynski, who teaches at Public School 123.

Once she learned the beeping sounds were cell-phone rings, she had to take a girl’s gadget away.

“She was … definitely upset,” said Wereszynski. “I held it at my desk. At the end of the day, I gave it back to her and the thing rang again.”

The incident prompted a conference with the child’s Spanish-speaking mother, a school aide acting as translator and Wereszynski. The mother wanted her child to have the phone in case she was running late to pick her up. After a long meeting, she reluctantly agreed not to send her daughter to school with a phone.

“I hear where the parent is coming from, but it is disruptive to the class,” Wereszynski said, adding that all the classrooms in P.S. 123 have phones.

Portland, Ore., mom Linda DeLacy said she gave her 10-year-old daughter a mobile so she could call when she’s leaving school and once she arrives home.

“I did it for my own peace of mind,” said DeLacy, 46, an office manager for the Oregon State PTA Board of Directors. “With all the stories of children being kidnapped … that’s the whole reason.”

DeLacy agrees phones should only be used for emergencies and understands the no-camera-phone rules, but she doesn’t like across-the-board bans.

“That would make me very unhappy if they said my daughter wasn’t allowed to call me when she’s leaving,” she said. “When it comes to my child’s safety and well-being, I’m not going to let a school push me around.”

Cresskill, N.J., mother Lisa Smith also gave her 9-year-old a mobile for safety reasons or in case there’s an unexpected change in schedules.

“She’s not allowed to use it in school during the day at all,” said Smith, 36, an internal auditor whose office is about 25 minutes away from her child's school. “In today’s world, I don’t want my kids to ever be afraid when things aren’t going as normal, when the ride isn’t there or cheerleading is canceled.”

The phones-in-school trend has caught on partly because the Amber Alert system has put more kidnappings in the media spotlight. Horrific memories of the Columbine High School massacre have also added to parents’ fears. And modern family dynamics have more moms and dads out working, increasing the reliance on mobile technology to communicate.

“It’s yet another example of a powerful form of technology entering our lives and breaking a bunch of rules all at once,” said Xeni Jardin, a contributing writer at Wired magazine.

DeLacy said her arrangement with her daughter has worked well, though she knows that could change in the rebellious teen years.

“She’s never misused it — I don’t know whether it’s just that she’s a plain old good kid or what,” she said. “There’s always kids that are going to push the envelope. Hopefully not mine.”

Jardin envisions a new invention spawning from the cells-in-schools explosion that will make everyone happy.

“There’s a huge market for a cell phone to come out that will only dial Mom and Dad,” she said.