Phonetics are used to help get your message across when the conditions are characteristically poor or there is interference about.

When using telephony, particularly under adverse operating conditions, words and callsigns may be misunderstood because of phonetic similarity.
To overcome this difficulty, phonetic alphabets are used. The following is the one recommended for use by ACMA: ARRL Phonetics

Girl hiking with hand-held device, using phonetics for better understanding