You can “Watch” you child’s cell phone because you see the cell numbers in and out on the bill. I am not sure that you can see the text numbers but I am quite sure you can’t see what is sent. People have a tendency to be careful what they say on a cell phone because it might cross with someone else’s and it is not as secure as a land line but texting does not have that kind of danger.
I was working with a family whose kid wound up in Juvy. I immediately asked the kids to give me his cell phone. You can’t imagine what I found on it. “where can I get a piece”, I immediately erased all the text messages just in case. This was a nebech situation, a dysfunctional single parent home, etc. WE worked with the judge and wound up sending him to a rehab out of town. He did well there.