30 CFR § 75.1600-3
Communications facilities; refuge alternatives
July 29, 2020
(a) Refuge alternatives shall be provided with a communications system that consists of—
(1) A two-way communication facility that is a part of the mine communication system, which can be used from inside the refuge alternative; and
(2) An additional communication system and other requirements as defined in the communications portion of the operator's approved Emergency Response Plan.
[73 FR 80700, Dec. 31, 2008]