Unless otherwise provided for by this Regulation, the competent institution of a Member State whose legislation makes:

• the acquisition, retention, duration or recovery of the right to benefits,

• the coverage by legislation,

  or

• the access to or the exemption from compulsory, optional continued or voluntary insurance,

conditional upon the completion of periods of insurance, employment, self-employment or residence shall, to the extent necessary, take into account periods of insurance, employment, self-employment or residence completed under the legislation of any other Member State as though they were periods completed under the legislation which it applies.