Cal. Gov. Code § 53115.3
When proposed implementation of the 911 system by a single public agency within its jurisdiction may adversely affect the implementation of the system by a neighboring public agency or agencies, such neighboring public agency may request that the office evaluate the impact of implementation by the proposing public agency and evaluate and weigh that impact in its decision to approve or disapprove the proposing public agency's final plan pursuant to Section 53115. In order to effectuate this process, each city shall file a notice of filing of its final plan with each adjacent city and with the county in which the proposing public agency is located at the same time such final plan is filed with the office and each county shall file a notice of filing of its final plan with each city within the county and each adjacent county at the time the final plan is filed with the office. Any public agency wishing to request review pursuant to this section shall file its request with the office within 30 days of filing of the final plan for which review is sought.
Ca. Gov. Code § 53115.3