Every provider of telephone service or other owner of a pay station telephone in an area served by an emergency telephone system established pursuant to this chapter must convert every pay station telephone to permit dialing 911 or the telephone company operator without deposit of a coin or other charge to the caller. Conversion must be completed by or before the time the emergency telephone system is operational. If modification of telephone service switching equipment is necessary to implement the provisions of this section, such modification shall be considered a cost of the emergency communications program and the provider of telephone service shall be compensated from the user fees authorized for this chapter upon application to the county, providing that such costs are approved by the public utilities commission.