@schnapps @Anonymous User
I guess BoroBoy is having the same problem I used to have, teenagers calling their friends mobiles using the house (land line) phone. And it costs a small (bankruptcy causing) fortune.
The way I used to handle it is by blocking all outgoing calls except 999 emergencies, and only allow outgoing once a secret code was typed in. Now, most telecom companies have this facility, as part of their arsenal of facilities, and there is no reason why Now TV should not have this facility too.
However, there are two problems:
You can never let your teenagers see you making a phone call, they'll memorise the secret code number.
The phone lock code should be different from the unlock one because, if they are the same, they will use "last number" redial to discover your secret code.
Apart from that.