The Best Numbers, the Best letters for DX Callsigns

One of the first decisions I face each ham dx adventure is selecting an appropriate suffix from the list provided to me by the relevant tele-communications authority.

The scarcity of activity from small Pacific islands means that, thankfully, I usually have quite a range of letter combinations available to me. 

Nonetheless, the choice is always well considered.



Whilst you can’t control the DXCC prefix when choosing a ham or 11m callsign, many guys target a suffix and blend of letters or numbers that have special significance.

The initials of their first and second name, for example, their school/ university, radio club, birth date, anniversary, etc.

Others seek short call signs or ones that spell 2-3 letter words commonly associated with the hobby or well-known hobby acronyms.

DX, DC / AC, YL, DOG, MAP, ASL, NIL, SWR, VIP, RAT, QRM, QRP, XYL, AUX, TRX, ANT, AGC, MIC, DAD, MUM, DIE and DIY are all suffixes found in my log in the past 12 months.

Quite often though, not enough thought is given to the ease with which the callsign can be received (RX) or even ‘enunciated’ over the air.


My experience undertaking Dxpedition work, and even at home in the shack, suggests that some callsigns are difficult to ‘get your ears around’.

Weak signals or high-listening-intensity environments such as contest or pile-ups (See left) only add to the complexity.

Ordinarily, callsigns which “roll” of your tongue are also easier to decipher.



Here’s my thinking around the best letters (and numbers) for callsigns for operation on any band.

For ham bands telephony, I suggest the following:

  • No doubled letters such as ‘KK’
  • B, C, D, E, G, P, T, V and Z sound similar, unless used phonetically
  • M, N, or F, S, X sound similar, unless used phonetically
  • Avoid the letter ‘F’Foxtrot is a poor choice in phonetics in my opinion as it’s actually made up of 2 small words with 2 distinctive sounds (i.e. Fox + Trot)
  • Stay away from the letters Delta, Golf, India, Lima, Mike, Papa, Quebec, Uniform and Victor as they’re the most difficult to enunciate.
  • Keep away from the letter ‘S for Sierra’ as the first part of the enunciation ‘CEE’ can be confused with letter ‘C’
  • Avoid ‘K’ as the last letter of your callsign – if on CW
  • Letters such as Echo, Hotel, November, Oscar and Tango slide off the tongue with much more ease.

As far as numbers for 11m callsigns goes, here’s how I see the digits 1-9 as choices for potential unit numbers…

1’s and 0’s are the most common digits featuring in my dxpedition logs and with good reason too.

The long ‘E’ sound in “ZE-RO” (0) and the one syllable short ‘U’ sound in “WUN” (1) are by far the easiest to decipher.

This is another reason why the combinations 001, 010, 011, 100, 101, 110 and 111 are the most attractive and eagerly sought after of unit numbers in DX Clubland, traditionally allocated to long term members, or Headquarters personnel.



The numbers “SEV-en” (7) and “TOO” (2) are not far behind the (0) and (1) when it comes to callsign articulation.

2 syllables and a short ‘e’ sound make (7) a very popular proposition with number groupings 007, 707, 107. 117 and 017 particularly appealing to serious DX Hunters.

Combining a (2) with (0) and (7) is also effective.

Units such as 021, 012, 201, 217, 212, 220 and 271 are not only easy to express but easy to comprehend in low conditions.

In contrast, “TREE” (3) and “AIT” (8) are tricky to vocalize, particularly after a few hours of continuous operation or 1 too many beers.


The most difficult numbers to untangle in a response to a CQ call tend to be “NIN-er” (9) and “FIFE” (5) which are too easily confused because of the identical long ‘I’ sound. 

For this reason, I’d stay well clear of the following unit numbers: 595, 955, 959, 559 and 995.

Good luck getting through a pile up with these ones hihi!


I hope you found my ideas and rationale around the choice of letters (ham) and numbers (11m) for callsigns enjoyable — or at the very least thought provoking.

I try to apply the same principles to QSY frequencies when “CQ’ing” on any one of the international call frequencies!

73 de Darren