That's why I really like the Tic Talk. YOU put in the phone numbers you permit, as well as the hours during which the numbers may be called. YOU set the limit on how many minutes can be used on the phone. YOU can call the phone any time, but the child can't unless you give permission. And your permission is remote, you set it online with a password only you know.
It also is very tough, can't be easily broken. And when I saw it displayed, they were even able to use it to track the phone - the parent could go online to see where the phone was and if the phone went "out of bounds" (limits set by parent) then the parent would be notified. "Out of bounds" also had a time limit, so a child could be out of bounds if they go home during the day, but not when they go home after school. Again, that would depend on whether this is available in your country. Australia is much more comfortable with "Big Brother" types of surveillance than the US, I gather.
Tic Talk has no camera, no texting, no email. There is no number pad at all. The numbers are already there (installed by parent, online) and the child scrolls through the list to make a call. For us, all calls made to the phone show up on the bill; who was rung and how long the call lasted. Our home phone bills have been like this too, for years, for all long-distance or mobile calls (local calls are not listed on the bill except as a tally).
When difficult child 3 was transferred to a school on the highway, we let him have a mobile phone because he was very anxious going to school such a long way from home. The school insisted that all mobile phones be left at the school office during school hours, or they would be confiscated. However, difficult child 1's & easy child 2/difficult child 2's high school permitted mobile phones; easy child 2/difficult child 2's first boyfriend asked her out via text message; the relationship was carried on almost entirely by text message and finally she broke up with him via text message. With hindsight, I really wish I'd bought a box of Tic Talk phones!
Marg