(1) Subject to paragraphs (2) and (3), traffic data relating to subscribers or users which are processed and stored by a public communications provider shall, when no longer required for the purpose of the transmission of a communication, be -

(a) erased;

(b) in the case of an individual, modified so that they cease to constitute personal data of that subscriber or user; or

(c) in the case of a corporate subscriber, modified so that they cease to be data that would be personal data if that subscriber was an individual.

(2) Traffic data held by a public communications provider for purposes connected with the payment of charges by a subscriber or in respect of interconnection payments may be processed and stored by that provider until the time specified in paragraph (5).

(3) Traffic data relating to a subscriber or user may be processed and stored by a provider of a public electronic communications service if -