47 CFR 80.1119 - Receipt and acknowledgement of distress alerts by coast stations and coast earth stations.
(a) Coast stations that receive a distress alert should defer acknowledgement for a short interval so that receipt may be acknowledged by a Rescue Coordination Center. Where an acknowledgement is not forthcoming within 3 minutes, the coast station in receipt of distress alerts must ensure that they are routed to a Rescue Coordination Center as soon as possible. Coast stations must provide assistance for distress communications when requested to do so by the U.S. Coast Guard. (This subpart does not specify any radio watches for coast stations.)
(b) Coast earth stations in receipt of distress alerts must ensure that they are routed as soon as possible to a Rescue Coordination Center. Coast earth stations must relay, as soon as possible, an acknowledgement of a distress alert from a Rescue Coordination Center.
(c) Certain messages must be carried without charge, regardless of the means by which they are transmitted:
(1) Distress alert messages;
(2) Search and rescue coordination messages;
(3) Medical assistance messages where an imminent danger to life is present, or
(4) Urgent meteorological or navigational danger messages passed in the ship-to-shore direction.