We have those in London too under the name InLink and are run by BT (the main telephone company here). BT used to offer free calls on them, but they had to stop because it was mostly being used by purchasers of drugs as an anonymous means of putting in an order. In terms of charging, they’re well used by homeless people.

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https://www.towerhamlets.gov.uk/News_events/2019/April_2019/...