Not so long ago I had to record a phone number by ear (also dictated by phone).
The phone was quite “beautiful”, albeit 10-digit. Approximately how: 8-916-120-20-23 (of course, all the numbers in this article will be fictional, invented at once). I did not like what was first said: one hundred and twenty, then the word twenty is repeated, then the twenty is repeated again, but with a troika at the end. Sometimes the effect is created that a person simply wants to say that the first 3 digits are 123. Or the first digits are 120, and then comes 23.
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When we dictate a phone number - we speak only numbers. We do not verbally say “transition to a new block of numbers”, which is visually indicated as a dash. The best and most natural designation is absolutely new numbers: if 123 goes first, then it can go 45 (or 54, or 64, or 41, or 52, or even 13, but by no means 23, 24, etc.) . A little better, but acceptable, if the next 123 numbers will be 34.
So, the perfect number for me looks like: abc-de-fg. Provided that the place "a" will not stand the number 9.
UPD. Here is another drawback of the kravis numbers: they are being tried to be remembered and often mistaken.