I am using a SIM card for mobile internet in my Lenovo X220 notebook. Each time when I start my system the PIN is required.
Does anybody know a way, how to make KDE remember the PIN? Can it be stored in kwallet or by ksecretservice?

Thanks in advance.

In the current implementation Plasma NM always asks for the PIN when ModemManager signals that it is required. There is no way to disable it.

OK, I posted this as a wish in the bug tracker.

Nevertheless, anybody else knowing a workaround?

You could likely setup a command using QDBus to send the PIN to Modem Manager ahead of time to get it to unlock the device. Best place to put this would probably be ~/.kde4/env/ or ~/.kde4/Autostart/.

Unfortunately you'll need to study the Modem Manager D-Bus API to determine if this is even possible - it may not be due to the architecture used by Modem Manager.

As I mentioned, I posted a wish at bugs.kde.org. here the link:
https://bugs.kde.org/show_bug.cgi?id=292477.

I will wait for that. As I do not use mobile connection very often, I will switch the device off via BIOS settings.