ELIZABETHTOWN — Essex County has moved one step closer to joining a multi-county lawsuit against four telecom companies.

The county Board of Supervisors authorized the signing of a retainer agreement with New York City-based law firm Napoli Shkolnik on Monday.

The law firm, which also represents the county in a lawsuit against opioid drug manufacturers, will be tasked with investigating whether there are shortfalls in revenue stemming from potentially inaccurate accounting by AT&T, Frontier Communications, Time Warner Cable and Verizon of the number of lines used by their customers to access 911 services and the revenue collected from those customers. After that investigation, the law firm will be asked to recommend whether Essex County should join Fulton, Nassau, Otsego, Schoharie, Sullivan and Wyoming counties in the lawsuit.

Under the terms agreed to by Essex County’s Board of Supervisors, Napoli Shkolnik will pay all costs stemming from the investigation and litigation unless the telecom lawsuit is won, in which case they’d receive an undetermined portion of the award.

The lawsuit alleges that local 911 services are underfunded as a result of the apparent failure of AT&T, Frontier Communications, Time Warner Cable and Verizon to accurately bill, collect and hand over revenue generated from 911 calls. The lawsuit was filed in state Supreme Court in Nassau County, Long Island on May 1. A representative from AT&T, spokesperson Brandy Bell-Truskey, has said the company plans to fight the lawsuit. A spokesperson for Verizon said the company doesn’t comment on litigation.

Essex County requires telecom companies to collect the maximum surcharge of 35 cents on calls from landlines and 30 cents on wireless and voice-over-internet calls to 911, according to county Treasurer Michael Diskin. Telecom companies that collect the charge can keep 2% of the revenue.

Last year, the county received $136,976 from telecom companies as a result of that charge. Diskin said the county has no way to tell if the revenue they receive is accurate, and the county is left to trust telecom companies to report both the number of lines that have used 911 services and the amount of money they’ve collected from the charge.