Japanese radiotelephony alphabet

The Japanese radiotelephony alphabet (和文通話表) is a radiotelephony spelling alphabet, similar in purpose to the NATO/ICAO radiotelephony alphabet, but designed to communicate the Japanese kana syllables rather than Latin letters. The alphabet was sponsored by the now-defunct Ministry for Posts and Telecommunications.

Each kana is assigned a code word, so that critical combinations of kana (and numbers) can be pronounced and clearly understood by those who transmit and receive voice messages by radio or telephone, especially when the safety of navigation or persons is essential.

There are specific names for kana, numerals, and special characters (i.e. vowel extender, comma, quotation mark, and parentheses).

Kana
Every kana name takes the form of a X no Y (X の Y). For example, ringo no ri (りんごのリ) means "ri of ringo". Voiced kana do not have special names of their own. Instead, one simply states the unvoiced form, followed by "ni dakuten". /p/ sounds are named similarly, with "ni handakuten". Thus, to convey ba (ば), one would say "hagaki no ha ni dakuten (はがきのハに濁点)". To convey pa (ぱ), one would say "hagaki no ha ni handakuten (はがきのハに半濁点)". As no word begins with the syllabic n, the word oshimai (おしまい), meaning end, is used for n (ん).

Numerals
Digits are identified with "数字の..." (sūji no.../Number X) followed by the name of the number, analogous to English phrases such as the number five.

When a number can be named in multiple ways, the most distinctive pronunciation is used. Thus 1, 7, 4 are pronounced hito, nana, yon rather than ichi, shichi, shi which could easily be confused with each other.