From the Microsoft.com/Security website, a revised set of recommendations for parents on mobile phone safety:
Mobile phone safety for kids
Mobile phones range from the most basic, like those for younger children that can place calls only to restricted numbers, to smartphones that are essentially tiny computers which offer:
Internet access to social networks such as Facebook, as well as to games, videos and video chat sites, TV shows, music, and applications (apps).
Use of camera and video that are fun, but also provide opportunity for bullies and others, and enable taking and sharing suggestive photos or videos (known as sexting).
GPS tracking that makes it possible to pinpoint the location of the phone—and the child. You can use this to monitor where your kids are, but if it is not used carefully, so can others. Furthermore, smartphones may tag a photo (geotagging), revealing precisely where and when it was taken.
Pick a service plan with the functionality and mobile phone safety features that are right for each child. Add features such as text messaging, photo-sharing, or Internet access only when you feel your child is ready to take on each new responsibility. Also, note that if you choose a billed plan, versus a prepaid plan, you can better monitor monthly charges, such as "free" offers with hidden monthly charges.
Agree on what features kids can use
Based on the age and maturity of each child, agree on phone features. Define clear rules for sensible use and the consequences for breaking them. Talk about usage: who they can talk to or text and when, the websites they can visit, and so on. With older kids, discuss cyberbullying and sexting.
From time to time, ask your kids to show you what is on their phones. Periodically re-examine rules as children mature and mobile technologies evolve.
Teach kids safe and responsible phone use
Help kids understand the following:
Share their phone number only with family and close friends. Do not put it on social network pages, use it to enter contests, or give it to just anyone who asks for it.
Lock the phone with a PIN that your child keeps secret (even from best friends) to prevent others from snooping or misusing it.
Don't say, text, or post anything that would hurt or embarrass someone.
Don't make, send, or accept provocative texts, photos, or videos.
Avoid clicking links in ads, contests, text messages (even from friends) offering free prizes and the like.
Get help from technology
Clearly explain why you are using safety tools and what they will do for your children's information security. Consider setting them up together.
Some protections are provided through the carrier's service; others can be set on the mobile phone. The most reliable are those on the phone, because when a phone uses a wireless network, it bypasses the carrier and its tools.
Filter or block websites and content as appropriate for your child's age and maturity:
Consider blocking Internet access for the youngest; for teens, think about restricting access to gambling, adult, and other inappropriate sites.
Filter lyrics, video, and other content that is violent or explicit.
Restrict access to forums (including in games) unless they are moderated by humans.
Use GPS cautiously. If you use a family location service to monitor your kids' whereabouts, make sure others cannot locate them. Otherwise, consider disabling the location feature on your child's phone; at the very least, turn it off in the phone's camera.
Manage contacts, which can include blocking callers and restricting contact to approved numbers only.
What to do if there are problems
Physical threats, persistent cyberbullying, or any form