That's the beauty of this forum. People doing things that they think is everyday and someone else thinks its a good idea. Just goes to show, no matter how simple your ideas, post it!
Excellent idea, my eldest has a mobile that I use to keep tabs on her, trouble is every time I ring her I can hear it ring in her bedroom and she is out somewhere.
Might look into it for my younger daughter (who has lost her phone and is not having another), which can then be passed on to Liam when he is older.