Recorder warning tone
type of call-progress tone
A recorder warning tone is a tone transmitted over a telephone line to indicate to the called party that the calling party is recording the conversation.
In the United States, the recorder warning tone is a half-second burst of 1400 Hz applied every 15 seconds. The recorder warning tone is required by law to be generated as an integral part of any recording device used for the purpose of recording telephone calls and is required to be not under the control of the calling party. The tone is recorded together with the conversation.
References
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22.
This brief starts where responsible research should: with the source description of “Recorder warning tone” as type of call-progress tone. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as type of call-progress tone. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Jun 22, 2026. The linked authority identifier is Q7302908. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1400 and 2022.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Recorder warning tone” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.