Claim forms: The insurer, upon receipt of a notice of claim, will furnish to the claimant such forms as are usually furnished by it for filing proofs of loss. If such forms are not furnished within 15 days after the giving of such notice the claimant shall be deemed to have complied with the requirements of this policy as to proof of loss upon submitting, within the time fixed in the policy for filing proofs of loss, written proof covering the occurrence, the character and the extent of the loss for which claim is made.