Is this still talking about outgoing calls?
I had this issue with android 9. Fixed by opening the dialler app, then /settings/calling accounts/Telekom(my operator)/GSM call settings/Additional settings/Caller ID/Show number
I’m connected on 4G most of the time but I guess my SIM doesn`t allow VoLTE so when I make a call it falls back to GSM/UMTS.
Not sure why network default isn`t to send the caller ID but this helped.