Hi Fredo,
As you figured out correctly Tchibo wants you to register your SIM. Usually that should have happend already upon purchase at your local Tchibo shop. But sometimes the shop employees forget to fax the registration form or it arrives illegible.
Now you can either register by phone or fill out
this form once more and drop it at a Tchibo shop or send it directly by fax to the number given on the form.
Regarding coverage, O2 doesn't have nationwide EDGE-coverage yet. They started EDGE-rollout last year, but their priority was rural areas where there's no 3G-coverage available. So especially in the bigger cities like Stuttgart there are still some GPRS-only cells, as there should be sufficient 3G-coverage.
The fact you are being served by a 2G-cell doesn't necessarily mean, that there's no 3G-coverage. Network operators define levels, when terminals should switch from one cell to another and they can also force terminals to switch to 2G-cells if a 3G-cell is congested (so called "overload protection"). You could try forcing your USB modem to use 3G only allthough reception could be low or the cell congested and so to ignore commands from the network. Therefore open Mobile Partner, go to
Einstellungen/Tools | Optionen/Options | Netzwerk/Network and chose only
3G/UMTS/WCDMA as
Netwerktyp/Network Type. Now check if you get reception, especially if it improves near windows. If so buy an USB-extension cable (I do recommend on with a foot like
this for € 6 incl. shipping) and place the USB modem on a window sill.
If you have bad luck and don't get any signal in 3G-only mode, switch Mobile Partner back to automatic network type selection.
Also note that on 3G networks there's an effect called cell breathing, which means that the coverage footprint of 3G cells varies dependant on the number of terminals and data throughput. So theoretically you could have 3G-coverage during the night, but not during the day.