Yes, this is a variant of many different "spelling alphabets" that came into being about at the time we started to have radio and phone communications. Since telephone communications, and later communications by radio, were/are not always of excellent quality, people started to create many variations on this theme. Such as the one you mention [mention]Helge.[/mention] .
Thank you for adding to this discussion, and this resource.
From the beginning of the 20th century , different "telephone" alphabets appeared in different countries, and among different sub communities in different countries.
But the development of international communications has also required standardization, whether in the field of aeronautics, maritime transport, telecommunications, the military field or emergency services. The "international" spelling alphabet is what has resulted to meet this need and is used as a standard across many countries and different languages for this reason.
And thus for myself - who not infrequently finds myself needing to communicate between people who speak different languages - to have a standard like this is most useful.
While in France, it is this standard using the International Radiotelephony Spelling Alphabet (IRSA) by Emergency services as well (I have a few friends in the Emergency services, including here in France). Also, when I am fortunate enough to go sailing, including in French waters, once again, it is the IRSA standard that is used.
Two concerns underlie the development of these alphabets.
In using these "spelling alphabets" the first concern is that the words corresponding to letters should not be easily confused (for example <p> and <b>, <t> and <d>) are clearly distinct.
The second concern is that the words used are sufficiently known to be immediately decoded. Which is also why having/being able to use a standard such is IRSA is so useful. Especially between people which have different languages and also different accents.
However, some other smaller communities do use some different standards, as you have mentioned.