47 CFR § 80.74 - Public coast station facilities for a telephony busy signal.

---
identifier: "/us/cfr/t47/s80.74"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 80.74 - Public coast station facilities for a telephony busy signal."
title_number: 47
title_name: "Telecommunication"
section_number: "80.74"
section_name: "Public coast station facilities for a telephony busy signal."
chapter_name: "FEDERAL COMMUNICATIONS COMMISSION"
subchapter_number: "D"
subchapter_name: "SAFETY AND SPECIAL RADIO SERVICES"
part_number: "80"
part_name: "STATIONS IN THE MARITIME SERVICES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "47 U.S.C. 151-155, 301-609; 3 U.S.T. 3450, 3 U.S.T. 4726, 12 U.S.T. 2377."
regulatory_source: "51 FR 31213, Sept. 2, 1986, unless otherwise noted."
cfr_part: "80"
---


# 80.74 Public coast station facilities for a telephony busy signal.

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%.