Call control can block the phone numbers of people with whom your children can not contact.
In this section of the administration panel, you can create a white list of phone numbers from the contacts of each device. This means that devices can only send and receive calls from numbers you have selected.
You can also block phone numbers that are unknown or even just those that are international, knowing which country are each one of them from.
Finally, you can have access to those numbers by including new telephone numbers on the agenda, or eliminating those which you don’t want the child to have in the device.
And all this from the administration panel.