(1) Without prejudice to any information requested pursuant to Regulation 98 and information and reporting obligations under national law other than the general authorisation, the Regulator may require an undertaking to provide information in respect of the general authorisation, of the rights of use for radio spectrum, of a right of use for numbers or of the specific obligations but only where such requirement is proportionate and objectively justified in particular for the purposes of -

(a) verifying on a systematic or case-by-case basis compliance with, as appropriate, condition 1 of Part A, conditions 2 and 6 of Part D, and conditions 2 and 7 of Part E of Schedule 1 and of compliance with any of the specific obligations,

(b) verifying on a case-by-case basis, compliance with conditions as set out in Schedule 1 where a complaint has been received by the Regulator, where the Regulator has other reasons to believe that a condition is not complied with or in the case of an investigation by the Regulator on its own initiative,