I install modem manager Gui.
Everything works fine except USSD option.
I get this error Error picture
then I try the command line
mmcli -m 0 --3gpp-ussd-initiate="*222#"
but I get same error.
error: couldn't initiate USSD session: 'GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Unsupported: Operation not supported.'
Can anyone help me to send ussd request?