Call Sign Variations

New hams listening in on a repeater are likely to hear a wide variety of call signs.  They may be confused and question some of them.  Repeaters near an international border can get pretty interesting with call sign variations in both countries.   EchoLink and IRLP open many repeaters up to access from anywhere the internet can reach.  Call sign variations are even more evident on HF bands where communication distances can be much greater.  New ham KG5XYZ may wonder why not everybody else is a KG5 like them.

It is important for new hams to be familiar with call sign variations and legal call signs for logging, message handling and just scribbling down a call sign when communicating with another ham.  “Did I just hear KMG365?” Comment if you get this reference. 🙂


First it is essential to understand that ham radio call signs (AKA call letters or just plain call) have a prefix followed by a numeric digit followed by a suffix.  The prefix is determined by the country in which the license is granted, most always one or two alphabetic letters. The digit following the prefix has significance within individual countries, such as geographic zones.  The alphabetic suffix following the number is generally meaningless other than to distinguish between calls sharing the same prefix and number.

There are variations in prefixes, not only by country but often also in number of alpha characters.  The number in a call sign is almost always a single digit.  The suffix may legally be anywhere from one to five alpha characters, depending on governing authority.

This arrangement of prefix-number-suffix is referred to as its format and is useful for describing a call sign. The format system counts the number of characters in both the prefix and the suffix.  It is usually termed the “p by s” system or pxs in writing where p represents the number of characters in the prefix and s is the number of suffix characters.  Using USA example call signs, W3MRC is a 1×3 call while KF5ZFD is a 2×3.  KL7AA and AF5NP are both 2×2 call signs.  NA6M is a 2×1 and W1AW is a 1×2.  One by three (1×3) and two by three (2×3) are by far the most common call formats in the US, followed by 2×2 and then 1×2 and 2×1.  Because they are relatively uncommon, even seasoned hams sometimes pause at a 2×1 call to register with their brain as legitimate.

1×1 call signs are legal in the US but are assigned only to organizations for special events and only for a limited time.  Details on special event call signs can be found at this FCC site.


Valid prefixes in the USA are K, N, and W (one letter),  and AA-AL, KA-KZ, NA-NZ, and WA-WZ (two letters).  Complete details can be found here.

Below is a small sample of international prefixes a US ham might run across, mainly on HF bands:

  • Canada- CY, VA, VE (most common), VO, VY, CY (less common)
  • Mexico- XE, XF
  • UK- G, M, 2E
  • Germany- DA thru DR
  • Japan- JA, JR
  • Brazil-  PPA thru PYZ
  • Netherlands- PAA thru PIZ
  • France- F
  • Russia- R, RA, RK, RN, RU, RV, RW, RX, RZ, UA
  • Australia- VK

A complete listing of international call signs can be found here and here and here and here .

New US ham calls are assigned by the FCC in the next available sequence by geographic region 1 thru 0.  For the foreseeable future,  prefixes will be two-letter ‘K’s regardless of region, except for Extra Class calls or new hams in Hawaii and American territories.  See topic What Will My New Call Sign Be? for more information.

Upon passing the exam, newly-licensed US hams will get calls assigned as just mentioned.  If you don’t like what you were assigned or just want something shorter or special (such as your initials), all hams can exchange it for an available call sign within their privileges.  This is known as a vanity call sign and is quite popular.

Format and characters of vanity call signs favors the highest class license, which is one of the perks of getting an Extra class ticket.  Technician and General class license holders can request an available 1×3 or 2×3 call with the K, N or W prefix and may choose the numeric digit (1-0).  The AA-AL prefix is available only to Extra class licensees.  Extras are also the only ones who can choose an available  1×2 or 2×1 call sign but these become available for re-assignment rather infrequently so there is fierce competition for them.  Look for a detailed post on vanity call signs in the near future.


Whether sequentially assigned or requested as a vanity call, the suffix SOS and common Q-code combinations are never assigned to avoid confusion.  Likewise a few obscure prefixes are unavailable for assignment.

Not too many years ago US call signs were more consistent and straight-forward.  ‘W’ prefixes were the rule;  Ks were infrequent and both Ns and A*s were very sparse.  The numeric digit was a pretty solid indicator of the FCC region in which the ham was licensed; if they moved outside their zone they would have to get a new call sign.  Call signs were predominantly 1×3 and 2×3 format.

When the Ks, A*s and Ns became more widely used, they also started issuing 1×2 and 2×1 routinely, until they used up those limited combinations.  The FCC also loosened up the restriction of call sign numeral to geographic region so that it is now portable (much like our mobile phone numbers).  So now we may have KA1s in Texas.  Factor in the popularity of vanity calls and a once-clean and uniform call sign system has been really muddled up.  All this contributes to the questions new hams may have over call sign variations.

To further confuse new hams monitoring local radio traffic, emergency communication deployments and public service events often use tactical call signs.  Tactical identifiers may be used to signify a position or function.  The radio operator assigned to that role or location is then conveniently identified as such when calling or being called during radio communications.  Typical examples of tactical calls are Net Control, Sag2, Water5, Red Team, and Checkpoint Alfa.  The use of tactical call signs is fine as long as the operator identifies with his/her legal call sign at the end of the transmission and every ten minutes as required by FCC rules.


In addition to all that has been presented on this topic in this post, there are good internet references found here and here and here and here.  Also some interesting history of amateur call signs here (you’ll have to scroll down a bit) and another good one here .

Regardless of country or location, an amateur radio call sign is unique to one station and/or operator so rest assured nobody else will duplicate your identity (legally).  Just wanted to leave you will a little peace of mind–  You are unique!

73, Jim  AF5NP

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