Spelling alphabet

If the speech connection via radio or telephone is so bad that uncertainties about the content can arise, the spelling alphabet has proven itself as an aid to communication. The letters to be transmitted are announced using unmistakable words.

ITU / ICAO / NATO spelling board on an old field telephone:

This link refers to the interesting Wikipedia page on the topic:

https://de.wikipedia.org/wiki/Buchstabiertafel#Internationale_Buchstabiertafel