The telephone company providing service within the geographical jurisdiction of a law enforcement unit shall inform law enforcement agencies of the address and telephone number of its security office or other designated office to provide all required assistance to law enforcement officials to carry out the purpose of RCW 70.85.100 through 70.85.130. The designation shall be in writing and shall provide the telephone number or numbers through which the security representative or other telephone company official can be reached at any time. This information shall be served upon all law enforcement units having jurisdiction in a geographical area. Any change in address or telephone number or identity of the telephone company office to be contacted to provide required assistance shall be served upon all law enforcement units in the affected geographical area.