47 CFR § 1.225 - Participation by non-parties; consideration of communications.
(a) Any person who wishes to appear and give evidence on any matter and who so advises the Secretary, will be notified by the Secretary if that matter is designated for hearing. In the case of requests bearing more than one signature, notice of hearing will be given to the person first signing unless the request indicates that such notice should be sent to someone other than such person.
(b) No persons shall be precluded from giving any relevant, material, and competent testimony because they lack a sufficient interest to justify their intervention as parties in the matter.
(c) No communication will be considered in determining the merits of any matter unless it has been received into evidence. The admissibility of any communication shall be governed by the applicable rules of evidence in § 1.351, and no communication shall be admissible on the basis of a stipulation unless Commission counsel as well as counsel for all of the parties shall join in such stipulation.