AT&T promotes their "smart limits for wireless" $5/month service to limit phone use for family plans.
It includes limits on texting -- except AT&T no longer cells a limited texting plan. It's only unlimited or .25/message. So this is really only useful if you want to disable texting, but you can call AT&T customer service and say you want administrative texting only -- for no charge.
The "smart limits" includes limits on data use -- except they don't work on a phone that might really use data:
Does Smart Limits for Wireless work for restricting all web browsing / data usage?We’re sorry, but Browsing Limits and Time of Day Restrictions will not block or restrict data usage through non-Media™ Net internet browsers. Certain data-centric devices such as BlackBerry® devices offer non-Media Net browsers. In addition, Browsing Limits will not block or restrict a user’s data usage if the user is also subscribed to DataConnect, LaptopConnect, Tethering (connecting a wireless device to a laptop) or Blackberry services, while the user is in WiFi mode, or while the user is using iPhone 3.0 software or later.
It also includes number blocking (could be useful) and "parental controls" which, I suspect, don't work on smartphones.
This service must be a money spinner, but, really, its obsolete. Not coincidentally, it's very hard to actually locate the link that allows one to configure this plan. We had it leftover from when it made sense; I was keeping it in part for the data limitation issues. Turns out that was a mistake.
Since this plan doesn't limit iPhone data, it means if you're purchasing a minimal 200MB/month data plan for a child with an inherited smartphone you have no way to prevent them going over their data limit and running up major fees. The best you can do is disable access to Safari, YouTube and the AppStore (AppStore allows video views). Note when App Store is disabled you can't install or update Apps!