15.—(1) A communications provider may override anything done to prevent the presentation of the identity of a calling line where—
(a)a subscriber has requested the tracing of malicious or nuisance calls received on his line; and
(b)the provider is satisfied that such action is necessary and expedient for the purposes of tracing such calls.
(2) Any term of a contract for the provision of public electronic communications services which relates to such prevention shall have effect subject to the provisions of paragraph (1).
(3) Nothing in these Regulations shall prevent a communications provider, for the purposes of any action relating to the tracing of malicious or nuisance calls, from storing and making available to a person with a legitimate interest data containing the identity of a calling subscriber which were obtained while paragraph (1) applied.