After installation and commencement of operation of a 9-1-1 system implemented pursuant to this act, all or part of the jurisdiction of a public agency within the county shall be added to the 9-1-1 service district pursuant to section 504 if both of the following occur:

    (a) The legislative body of the public agency adopts a resolution including all or part of the public agency within the 9-1-1 service district.

    (b) A certified copy of the resolution adopted by the legislative body of the public agency is forwarded by certified mail, return receipt requested, to the county clerk.