Download the files linked below to aid your efforts in identifying unusual call signs heard on the air. (The two Call Sign Prefix Assignment files are in PDF format.)

Call Sign Prefix Assignments – Sorted in prefix series order: Click here

Call Sign Prefix Assignments – Sorted in country order: Click here

Download the official ITU Prefix Assignment table here: https://www.itu.int/en/ITU-R/terrestrial/fmd/Pages/call_sign_series.aspx

ABOUT CALL SIGN PREFIXES

Regulation of the RF spectrum is the responsibility of the International Telecommunication Union (ITU).

The ITU is an agency of the United Nations, headquartered in Geneva, Switzerland. Among their many responsibilities are maintaining worldwide “law and order” throughout the RF spectrum.

In essence, the ITU writes the rules and guidelines that individual governments are expected to follow. In the United States, the agency charged with regulating RF in compliance with ITU guidelines is the Federal Communications Commission (FCC).

Concerning amateur radio, one responsibility of the ITU is the allocation of call signs prefixes.

To both new and experienced hams call signs can be confusing at times. For example, calls beginning with AA to AL prefixes are United States calls, but the AM prefix is assigned to Spain. Another example is Great Britain. While G is the commonly known British prefix, 2A is now also a British prefix.

Another sometimes confusing example involves the F prefixes, which are allocated to France. France sub-allocates some F prefixes to its territories and possessions. For example, FA is assigned to Guadeloupe and FM is assigned to Martinique.

Should you need a reference to call sign prefixes, refer to the files linked above for the official 2026 ITU Amateur Radio Prefix Assignments.