47 C.F.R. § 80.74 Public coast station facilities for a telephony busy signal.
Title 47 - Telecommunication
A “busy” signal, when used by a public coast station in accordance with the provisions of §80.111(d), must consist of the transmission of a single audio frequency regularly interrupted, as follows: (a) Audio frequency: Not less than 100 nor more than 1100 Hertz, provided the frequency used for this purpose will not cause auto alarms or selective-ringing devices to be operated. (b) Rate of interruption: 60 times per minute ±10%. (c) Duration of each interruption: 0.5 second ±10%.
Title 47: Telecommunication
PART 80—STATIONS IN THE MARITIME SERVICES
Subpart C—Operating Requirements and Procedures
Station Requirements—Land Stations
§ 80.74 Public coast station facilities for a telephony busy signal.
