Broadmobie BM818 Does not expose USSD interface

I wanted to use ppm to check my prepaid balance but it did not find MMs USSD interface:

on the l5:

gdbus introspect --system --dest org.freedesktop.ModemManager1 --object-path /org/freedesktop/ModemManager1/Modem/0  | grep -i ussd
[nothing]

but on my laptop

gdbus introspect --system --dest org.freedesktop.ModemManager1 --object-path /org/freedesktop/ModemManager1/Modem/0  | grep -i -A12 ussd
  interface org.freedesktop.ModemManager1.Modem.Modem3gpp.Ussd {
    methods:
      Initiate(in  s command,
               out s reply);
      Respond(in  s response,
              out s reply);
      Cancel();
    signals:
    properties:
      readonly u State = 1;
      readonly s NetworkNotification = '';
      readonly s NetworkRequest = '';
  };