Want to know if you can get a home phone with lock to stop outgoing calls?

In the days when we only had the GPO phone system my sister-in-law received an enormous bill one quarter because her sons were phoning their girl friends; she made them pay their share of the bill by getting the GPO to install a coin box like the ones in telephone boxes so the boys had to put the money in. I think there was a rental fee for the box; admittedly it was an inconvenience for her, but it certainly saved her a lot, both in arguments and in money. Don't know if you can still do this.