If I understood correctly, you called a number and it RANG AND RANG… is that what you mean?

Otherwise a “series of long beeps” is what we more succinctly call a BUSY SIGNAL.

When nobody's there - we call it длинные гудки;
When the line is busy - короткие гудки.
Два человека пытаются дозврниться домой товарищу:
1).
A: Ну что, дома он?
В: Не-е, никто трубку не берёт, и длинные гудки.
2).
А: Ну что, дома он?
В: Вроде да: короткие гудки - болтает с кем-то

oh hey Uly! long time no see :) yeah, when you call someone and they don't pick up, what do you here? I was thinking maybe it's "long tones"? and when the line is busy it's "short tones"

OK, thank you for the explanation. I would say “a series of long beeps“ and “a series of short beeps“. Or, if you want to be less precise and literal, you could just say the phone rang and rang and nobody picked up, and you got a busy signal, both of which sound perfectly correct and natural.

thank you Uly, you're very helpful as usual!

👍🏼🤩

короткие гудки -
https://www.collinsdictionary.com/dictionary/english/engaged-tone
https://en.wikipedia.org/wiki/Busy_signal

длинные гудки -
https://en.wikipedia.org/wiki/Ringing_tone