This WWAN card is included in my Lenovo Thinkpad X201.
systemctl enable ModemManager
systemctl start ModemManager
I couldn't create a mobile connection using the KDE GUI of network manager; instead I needed to set the connection up with nmcli:
nmcli connection add type gsm ifname DEVICENAME apn pinternet.interkom.de
You get the DEVICENAME via
nmcli d | grep gsm
Sometimes the mobile connection does not appear even if the modem is enabled. In this case start the networkmanager gui, edit the mobile connection entry and click on „Ok“ or „Save“. Now „Connect“ is available for the connection and it appears in the available connections.