---
kind: "section"
citation: "47 C.F.R. § 80.74"
title: "47"
number: "80.74"
heading: "Public coast station facilities for a telephony busy signal."
url: "https://uscodex.org/cfr/47/80.74"
---

# §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)](/cfr/47/80.111.md?p=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%.

## Notes

### Authority

Authority: 47 U.S.C. 151-155, 301-609; 3 U.S.T. 3450, 3 U.S.T. 4726, 12 U.S.T. 2377.

### Source

Source: 51 FR 31213, Sept. 2, 1986, unless otherwise noted.