Mont. Code Ann. § 69-3-804

Construction, maintenance, or operation of a private telecommunications service does not constitute the provision of regulated telecommunications service, and a private telecommunications service is not subject to any of the provisions of this title. If any other person or entity, including the owners or shareholders of the entity owning or operating a private telecommunications service, uses the telecommunications service, whether for hire or not, the private telecommunications service is a regulated telecommunications service under this part. An occasional or accommodative use of a private telecommunication system by a third person is not a violation of this section.