General · EdgepediaSeptember 17, 20267 min read

Station identification

Station identification is the periodic announcement or display by which a licensed broadcast station states its call sign and community of license, required by regulators so that listeners and viewers can tell which station is transmitting at any moment. In the United States the Federal Communications Commission (FCC) governs the practice under 47 CFR § 73.1201, which requires identification at the beginning and end of each day's operation and hourly, as close to the hour as feasible, at a natural break in programming.¹ Internationally, Article 19 of the ITU Radio Regulations sets the rules for identifying stations across radiocommunication services.²

Key fact	Detail
When required	At the beginning and ending of each time of operation, and hourly, as close to the hour as feasible, at a natural break in program offerings¹
Required content	Call letters immediately followed by the community or communities specified in the station's license as its location¹
Permitted insertions	Licensee name, frequency, channel number as stated on the license, and/or network affiliation, between call letters and location; no other insertion is permissible¹
TV multicast channels	A station with major channel 26 may identify an HDTV service as 26.1 and an SDTV service as 26.2¹
Digital identifiers	Transport Stream ID (TSID) values, two sequential numbers per station, are assigned by the FCC; TV and Class A TV stations transmit the odd-numbered TSID, and ATSC 3.0 stations use the even-numbered value as their Bit Stream ID¹
International basis	Article 19 of the ITU Radio Regulations lists the services that must carry identification signals and the means of identification, including call signs²

The FCC rule: timing and content

Under § 73.1201(a), broadcast station identification announcements must be made at the beginning and ending of each time of operation and hourly, as close to the hour as feasible, at a natural break in program offerings. Television and Class A television stations may make these announcements visually or aurally, which is why a small on-screen rendering of the call sign can satisfy the requirement.¹

The content rule is deliberately narrow. For official purposes, a station identifies itself by giving its call letters and then, right after them, the location named in its license, which may be one community or several. Between the call letters and the location, a station may insert the name of the licensee, the station's frequency, the channel number as stated on the license, and/or the network affiliation; the rule states that no other insertion is permissible. A station may add the names of additional communities, but the licensed community must be named first.¹ A court reviewing the rule in Sudbrink Broadcasting v. FCC observed that while identification announcements are not the most significant portion of a radio station's program day, they are among the most highly regulated.³

Digital television and radio

Multicast channels. A TV station that includes its channel number in identification must use its major channel number and may distinguish multicast program streams. As an illustration in the rule itself, a broadcaster whose major channel number is 26 could label an HDTV service as 26.1 and an SDTV service as 26.2. A station devoting one of its multicast streams to another licensee's programming must identify itself and may also identify the source, using a prescribed format; in that case the identification may not include the frequency or channel number of the program source.¹

Machine-readable identifiers. Beyond the human announcement, the FCC assigns Transport Stream ID (TSID) values, identification numbers stored in the Commission's online database, with two sequential values per station. All TV and Class A TV stations must transmit their assigned odd-numbered TSID. In the ATSC 3.0 broadcast standard, a similar value called a Bit Stream ID (BSID) is used, and stations operating in ATSC 3.0 mode use their assigned even-numbered TSID as the BSID.¹

Digital radio. A radio station operating in DAB hybrid mode or extended hybrid mode must identify its digital signal, including any free multicast audio programming streams, in a manner that appropriately alerts the audience that it is listening to a digital audio broadcast.¹

Special situations

The rule accommodates several operating arrangements. When the same licensee operates an AM station in the 535–1605 kHz band and another in the 1605–1705 kHz band, both licensed to the same community and simultaneously broadcasting the same programs, a single joint identification may serve both stations during the simulcast. When programming is rebroadcast simultaneously over a satellite station, the originating station may make the identification announcements for it; for television this must include the channel number of each station, and for aural stations the frequency of each.¹

Low power television stations follow their own section, § 74.783. An LPTV station originating programming may use the § 73.1201 procedures on its primary stream; otherwise it may transmit its call sign in the short channel name field of the Program and System Information Protocol (PSIP) or its ATSC 3.0 equivalent, or arrange for the primary station whose signal it rebroadcasts to identify it visually or aurally. Translator licensees using that last method must secure an agreement with the primary station to keep the translator's call letters, location, and contact information on file for FCC inspection.⁴ Auxiliary and pickup stations have parallel duties: a television broadcast auxiliary station with transmitter output of 1 watt or more must identify at the beginning and end of each period of operation and hourly, by its own call sign, the call sign of its associated TV station, or the call sign of the station being relayed or the network identification.⁵

A 2007 FCC rulemaking (FCC 07-205) proposed amending § 73.1201 to add a public-file notice: twice daily, television station identification would have to include a notice of the existence, location, and accessibility of the station's public inspection file, with at least one announcement between 6 p.m. and midnight.⁶

The international framework

Station identification is not a purely domestic practice. Article 19 of the ITU Radio Regulations contains the international rules: it lists the radiocommunication services that should carry identification signals, including amateur, broadcasting, fixed below 28 MHz, mobile, standard frequency and time signal, and radiobeacon services, and explains the means of identification and their formation. Under RR19.40, the same call sign, maritime mobile service identity, selective call number, or identification number shall not be assigned more than once, and under RR19.16 a station may be identified by a call sign, a maritime mobile service identity, or other means such as the name or location of the station, the operating agency, or a characteristic signal.² The ITU describes the identification code as a kind of passport for a radio station, used for locating sources of interference, organizing rescue operations for ships or aircraft in distress, and identifying emissions during radiomonitoring.²

Call signs behind the identification

The call letters that anchor every identification trace to the London International Radiotelegraph Conference of 1912, which assigned the letters W, K, N, and part of the A series to the United States; W and K went to commercial broadcasters while N and A were allocated to military users.⁷ Around 1928 the Federal Radio Commission formalized rules requiring four-letter combinations, with initial W for stations east of the Mississippi River and initial K for stations west of it; stations already on the air were allowed to keep their existing call letters regardless of number or location, which is why pioneer stations such as KDKA in Pittsburgh and WGN in Chicago remain exceptions to the geographic pattern.⁷ Three-letter call signs, assigned to AM stations largely between 1921 and 1930, survive in continuous use under a grandfathering exception in the FCC's call sign rules.⁸

Because the identification requirement ties each announcement to a specific call sign and community, the practice also shaped station branding: stations chose call letters that doubled as slogans or channel references, such as KTWO in Casper, Wyoming, and WPVI in Philadelphia, where the Roman numeral VI marks the channel 6 assignment.⁷

References

Topic: Encyclopedia › Society and history › Broadcasting and journalism › Broadcast organizations and stations › Individual broadcast stations, lists, and call signs › Individual broadcast stations (overview)

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 25, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026

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