Is there a GUI for ModemManager ?
No
In order for NetworkManager to recognize your mobile broadband you need
ModemManager to be enabled and started automatically each time the system
start up. We use "systemctl" to enable, disable, start and restart system
services.
the command i posted up must be executed as root(when we use #, it means that
command can be only run-ed by root ) or be run-ed by using sudo.
Open the terminal and type:
$ sudo systemctl enable ModemManager
$ sudo systemctl start ModemManager
if you use sudo, type your own password.
$ sudo -i // use it to become root user
