How does changing the dialed number work on android?

Question

Android

I have repeatedly noticed that on android the dialed number can change after picking up the handset. For example, when calling to some 8 800, the numbers to which they are forwarded are displayed, or when calling to some landlines, a full number is given instead of an abbreviated one, or vice versa. Also, sometimes when calling to a mobile via 89xxxxxxxxx, +79xxxxxxxx is displayed.
There is an intuitive feeling that the number comes from the telephone network, but where can I read about it? I also remember that in ancient times on some of the first Siemens mobile phones there was a similar situation.