Before you shudder, think about the times you WANT them to call. And then about how few phones are around these days.
Firefly thought about this, and did it right. They set up a phone that only goes to preprogrammed numbers and 911, so you know who could be called, or be calling, your kid. And it comes with fixable times so you know it isn't a three hour phone call every evening you're paying for.
Check it out. I'm still going to wait a bit before Joy gets one, but I know what she'll be getting.