Callsign Prefix Lookup
Check a callsign’s format and see which country its prefix is allocated to.
Lookup
Why callsigns start the way they do
Every country that participates in amateur radio is assigned one or more prefix blocks by the International Telecommunication Union, so that hearing the first letter or two of a callsign tells you roughly where in the world the station is. The call-area digit that follows often narrows it further, to a region within that country.
This is one reason experienced operators can often guess a contact's location just from the first syllable of their callsign — “Whiskey-one” is instantly recognizable as an East Coast US station, the same way “Juliett-Alpha” signals Japan.
Frequently Asked Questions
What makes up a standard amateur callsign?
A prefix (one to three letters, occasionally starting with a digit, like "4X" or "9V"), a mandatory call-area digit, and a suffix of one to four letters. For example, in W1AW, "W" is the prefix, "1" is the call area, and "AW" is the suffix.
How does the prefix tell you the country?
The ITU allocates blocks of prefixes to each country in the Table of International Call Sign Series — for example, callsigns starting with K, W, or N are United States amateur stations, G is the United Kingdom, and JA is Japan. This tool checks a simplified, commonly seen subset of that table, not the full official list.
Why does an unrecognized prefix still say "valid"?
"Valid" here means the callsign matches the standard prefix + call-area digit + suffix shape, which many countries' allocations follow. Not finding a country just means that particular prefix isn't in this tool's reference table — it doesn't mean the callsign itself is fake.
Is this a live registry of licensed operators?
No. It doesn't check whether a specific callsign is currently issued to anyone — it only checks the format and looks up which country's prefix block it falls under. For an actual license lookup, use your national radio authority's official database (such as the FCC ULS in the United States).
Educational tool only. This is a simplified reference, not the full ITU Table of International Call Sign Series or a live license registry — confirm anything official with your national radio authority.