The key is to look up your local city or county franchise agreements for ISP right-of-ways and then contact those people and that agency. They should be Google-able because they’re public record. In the US, anyway.
That doesn't actually work here in my part of NM. The company is the phone company, the wiring was installed on the same easements that they used to provide phone service. The problem is that the PUC, which controls phone service, has no jurisdictional authority under state law over internet service (and neither does any other state agency). At least this is what the PUC told us during a multiway zoom meeting between residents, the phone company/ISP, the PUC and two county commissioners.
