During continued substantial compliance with the terms of this article by the owner of the telephone exchange (or company rendering telephone service within the limits of said municipality), the charge levied hereby shall be and continue to be in lieu of all concessions, charges, excises, franchises, licenses, privileges and permit fees, taxes or assessments except ad valorem taxes; provided, that, it is not intended hereby to extinguish or abrogate all existing arrangements whereby said municipality is permitted to use any underground conduits, duct space or pole contracts of said company.