On and after the ninetieth day following the effective date of this amendment, every telephone directory thereafter distributed to the members of the general public in this state or in any portion thereof which lists the calling numbers of telephones of any telephone exchange located in this state shall contain a notice which explains the offense provided for in section 540a, such notice to be printed in type which is not smaller than any other type on the same page and to be preceded by the word "warning" printed in type at least as large as the largest type on the same page: Provided, That the provisions of this section shall not apply to those directories distributed solely for business advertising purposes, commonly known as classified directories, nor to any telephone directory first distributed to the general public prior to the date specified above. Any person, firm or corporation providing telephone service which distributes or causes to be distributed in this state 1 or more copies of a telephone directory which is subject to the provisions of this section and which does not contain the notice herein provided for shall be guilty of a misdemeanor.