UK Privacy and Electronic Communications Regulations 2003 (PECR) Reg.11: Regulation 11: Called-subscriber controls over calling and connected line identity

For incoming calls, where the relevant facility exists, the provider must give the called subscriber simple means to stop the calling line's identity being presented, free for reasonable use; to reject incoming calls whose caller has withheld their identity, where identity can be presented before the call is set up; and to stop, without charge, presentation of the connected line's identity to the caller.