Is Fonic inside of this package: How will APN settings work? - #9 by Quarnero Also, thanks for bringing this issue forward!
apt list mobile-broadband-provider-info
apt list prepaid-manager-applet
sudo apt install prepaid-manager-applet
For example, after installation of prepaid-manager-applet might (at least) recognize which provider used there:
As @guido.gunther already wrote to us: “It uses ModemManager (the GSM and 3G helper of NetworkManager) to talk to the modem and mobile-broadband-provider-info to determine the necessary USSD codes for your provider.”