What is a ham radio call sign?

How do you read a call sign?

Read it in three parts. The prefix, one or two characters, names the country. One digit follows. The suffix after it, up to four characters ending in a letter, identifies the holder. In UA3CR, UA is Russia, the 3 with the letter C points to Moscow, and CR is the holder.111

The ITU rule (Radio Regulations No. 19.68) allows a one-character prefix only for B, F, G, I, K, M, N, R and W. Every other country needs two characters. Then come one digit and up to four characters, the last a letter. For special occasions a country may allow longer call signs.1 In 1947 the suffix was capped at three letters.3

To make a call sign in your country's own pattern, or to decode any call sign, use the call sign generator.

Which prefix belongs to which country?

The ITU's Appendix 42 gives every country one or more blocks. Ten series belong whole to one country, so one character is enough: K, N and W are the US, G, M and 2 the UK, F France, R Russia, B China and I Italy. Everyone else needs two characters, such as JA for Japan or 4X for Israel.12

Source: ITU table of call sign series.2

Some prefixes start with a digit, like 4X (Israel), 5B (Cyprus) or 9A (Croatia). The ITU explains that the old three-letter series ran out, so it added new ones. The digit in front is never 0 or 1. Digit series from 2 to 9 were already in the 1947 table.13

What does the digit in a call sign mean?

It depends on the country. The ITU only asks for one digit between prefix and suffix. The US, Japan, Canada and Australia use it for a region. Russia pairs it with the next letter to name the region. The UK and France use it for the license level instead.14710

Can you choose your own call sign?

In some countries, yes. A US ham can request a vanity call sign: up to 25 choices in order of preference, for $35. UK applicants pick the prefix and letters when they apply online. Australia charges more for a call sign you choose. In Latvia you choose the last letter. Russia and Japan assign call signs without asking.56715131112

A US call sign rests for two years after it expires or its holder dies. Then anyone eligible can ask for it.5 Senator Barry Goldwater held K7UGA until his death in 1998. In 2000 the FCC gave it to a club, the Central Arizona DX Association.32 Vanity letters often mean something: country guitarist Chet Atkins held W4CGP, for "certified guitar picker".39

Why did the Soviet Union use UA?

UA was never the whole Soviet Union. The 1947 ITU table gave the USSR the R block and most of the U block. Inside the country, the second letter pointed to a republic, and UA was the Russian one. Today UA to UI belong to Russia, UN to UQ to Kazakhstan and UR to UZ to Ukraine.3202

According to a commonly cited table of Soviet prefixes, Ukraine used UB5, Belarus UC2, Latvia UQ2 and Estonia UR2.20 In the 1947 ITU table the Ukrainian SSR and the Belorussian SSR were also listed with series of their own.3

RAEM: a call sign with no digit

RAEM breaks the pattern: four letters and no digit. It was the radio call sign of the steamship Chelyuskin, which sank in the Arctic in 1934. Its radio operator, Ernst Krenkel, kept it as his personal call sign.18 When Soviet hams got their QSL cards through Box 88 in Moscow, Krenkel was allowed his own address and the non-standard RAEM.19 Russian rules still name RAEM as an exception. Once a year, for up to 24 hours, it goes to a station in the contest held in Krenkel's memory.11 The 53rd contest ran on December 28, 2025.17

Whose call sign was UA3CR?

UA3CR belonged to Leonid Labutin (1928–1998), a Moscow radio engineer. He got it on March 22, 1949, and his name is tied to the first single-sideband, satellite and packet radio systems in the USSR. On June 28, 1987, he made the first packet radio contact in the USSR, Moscow to Indonesia.16

• 1958. His first single-sideband (SSB) contact, on 20 m, with a 12-crystal filter he built himself. He then led the USSR group that promoted SSB and wrote the SSB column in the magazine Radio.16
• 1961. With the American Don Stoner, W6TNS, he proposed a joint amateur satellite on a Soviet rocket. The authorities refused, and the Americans launched OSCAR-1 on their own on December 12, 1961.16
• 1978. He ran the Moscow command station for the first Soviet amateur satellites, the RS series, launched on October 26, 1978.16
• 1987. The first packet contact in the USSR, UA3CR to YB6MF in Indonesia, with a TNC-2 controller given by Tom Atkins, VE3CDM, president of the Canadian Radio Relay League.16
• 1988. In November the first packet bulletin board in the USSR went on the air. The same month, UK3KP, the club station of the newspaper Komsomolskaya Pravda, made the first amateur contact with the Mir space station, with Labutin at the radio. At an AMSAT meeting in the US he passed all the US exams in one sitting and got the Extra class call sign AB4LZ.16

The AMSAT-R note on his death calls UA3CR "a call sign known worldwide".16

Famous people and their call signs

Kings, astronauts, a Nobel laureate, a German chancellor and rock musicians have held ham call signs. Click a call sign to decode it in the call sign generator. For people who have died I write "held": in the US a call sign can pass to someone else two years after the holder's death.5

Yuri Gagarin was not a ham. The story of his "call sign UA1LO" goes back to a 1962 QSL card signed "Yuri". AMSAT-UK found that UA1LO belonged to Yuri Babkov of Saint Petersburg.44

How do you get a call sign?

Pass your country's amateur radio exam and apply for a license: the call sign comes with it. In the US the FCC license costs $35 and brings a call sign from its list. In the UK the online application is free and you choose the call sign. US call signs can be looked up in the FCC's ULS.46721

More on exams and license classes is in What is ham radio?. Once on the air, you must say your call sign: US rules ask for it at the end of each contact and at least every 10 minutes.22

Does a PoC radio need a call sign?

No. A PoC radio talks over the mobile network, not on ham frequencies, so it needs no radio license and has no call sign. People in a push-to-talk app are known by their account name. Ham rules require a call sign because every station on the air must identify itself.22

If you want to talk across a city or a country without an exam, see What is a PoC radio? and the types of two-way radio.

Questions

Sources

1. Radio Regulations, 2024 edition: Article 19 (Nos. 19.40, 19.50, 19.68, 19.68A) and Resolution 13 · ITU
2. Table of allocation of international call sign series (Appendix 42) · ITU
3. Radio Regulations, Atlantic City 1947: Article 19 and the table of call signs · ITU
4. Amateur Call Sign Systems · FCC
5. 47 CFR 97.19: Application for a vanity call sign · eCFR, FCC
6. 47 CFR 1.1102: Schedule of charges for applications in the wireless telecommunications services · eCFR, FCC
7. Amateur radio licensing guidance for licensees (October 2025) · Ofcom
8. Rufzeichenplan für den Amateurfunkdienst in Deutschland (valid from April 1, 2025) · Bundesnetzagentur
9. Amateurfunkverordnung § 10: Rufzeichenzuteilung · German federal law
10. Arrêté on amateur operator certificates and call signs, Annex II (2018, copy) · French Ministry of Economy, copy on Le Radioscope