MC7700 in a CF-30

Hi folks!
I am a newby here and starting my presence right with a challenge. May be some of you own a CF-30 as well and are not happy with the build-in 3G-option. So am i. So i bought a MC7700 on Ebay and installed it. At first, there was no card detected at all. Meanwhile i got that far, that the hardware-manager shows me all the components in working condition and with the tool mwconn i can scan the available networks. But i don’t get a final connection. Also the Sierra-Watcher (Skylight) ist not showing any device.
How can i get this to run? Any hints? I am located in Germany, using T-Mobile as the provider. Running Windows 10.