HOUSTON -- For parents of teenagers, not knowing where your child is can be frustrating, even frightening. Giving them a cell phone doesn't always mean they'll answer.That's why a Houston mom took control and invented an app that her kids -- and your kids -- can't ignore.Sharon Standifird was livid the day she called and texted her children and they didn't respond."It went from a frustration to a worry," Standifird said.Once she knew they were safe, but ignoring her calls, she got an idea."We need to develop an app that just shuts their phone completely down and they can't even use it," she said. "I got on the internet and I literally just started researching how to develop an app."Her husband said he wasn't surprised."Anything she's really set her mind to, she's done," William Standifird said.She has climbed Mount Kilimanjaro and has even served in the Gulf War."We did patrolling as military police. So we did convoys, security, escorts and things like that," Sharon Standifird said.Becoming an app developer was just one more challenge for this mom on a mission. After months of design and working with developers, the 'Ignore No More' app was born."This is the parent phone and this is the child phone. As a parent, all I have to do is touch the app. I simply tap his name," said Standifird. "To lock Bradley's device, enter at least a 4-digit unlock code below. I'm going to re-enter it and now I'm going to press 'Lock Bradley's Phone.' And if you watch Bradley's phone, it's going to go blank. Bradley would pick his phone up and once he activates his phone, he's going to see that it's locked."With one tap, a list of only parent-selected contacts comes up. The child can call someone on that contact list and get the password to unlock the phone."It takes away texting, it takes away gaming, it takes away calling their friends, surfing the internet. If there's an emergency, the child will always be able to call 911. It's a feature that no developer can take off the phone," she said.How does her son feel about it?"Well, I thought it was a good idea, but for other people, not me," Bradley Standifird said.But mom says the app appears to be working."I do have to say that he responds to my texts and my calls a whole lot quicker than he used to," Sharon Standifird said.The Ignore No More app is $1.99 and only available for Android phones on Google Play. To download it,Sharon Standifird is working on an iPhone version that will be released soon.Other apps for parents:DinnerTime helps parents remind their children about taking time out from their mobile devices to study, get the sleep they need, and of course, enjoy mealtime as a family. Features include Dinner Time, Bed Time and Take a Break control options.Canary raises an alarm to parents and sends them immediate alerts when their teens are texting, talking on the phone or using social media while on the road. Canary knows when your teen unlocks their phone and alerts you when they are riding in a car going over 12 mph.Use AppCertain to manage your kids' app use by keeping track of all the apps your kids have downloaded and knowing more about those apps. There is also a curfew mode to turn off the child's access to apps.Norton Family keeps you in the know about which websites kids visit and helps avoid unsuitable content. The app sends you an email when kids attempt to visit a blocked site, so you can start a conversation about appropriate content.Mobile Watchdog provides parents with over 20 parental controls that didn't come standard on your child's phone. Monitor text messages, photos, call history, and Internet usage. Parents can also designate certain time slots to restrict usage and block certain apps from working. It also comes with GPS tracking to know where the phone is at all times.