According To BT using ACR can cause you problems.

"What are the potential security and safety concerns with Anonymous Call Rejection?

Many public services such as the police force, the DSS, hospitals, fire brigades and public utilities will not be able to contact customers who use Anonymous Call Rejection.
This is due to the configuration of their private switchboards. This problem will also affect many UK businesses. We're trying to find a solution for these problems."

http://bt.custhelp.com/app/answers/detail/a_id/8482

bigjohn wrote on Jan 21^st, 2014 at 11:05am:


So why does OfCoN allow BT Openreach to charge (and also to overcharge violenty in relation to its possible benefits) for a service that is clearly Not Fit For Purpose.  Also these public bodies will only have a problem contacting people because the same stupid OfCoN repeatedly did nothing to combat the huge number of businesses configuring their CLI as Unavailable.

Whenever I copy Ofcom's supposed telecoms expert, Mr Steve Unger or their supposed Consumer Affairs expert, Mr Claudio Pollack, in to pertinent correspondence on this or any other issues I find that I will always get a big fat zero back by way of response.