[inquisitor]

Marco, you can provide the address of your hotel or any other existant German address.

You can neither activate nor recharge a Fonic SIM at Lidl. Lidl does only sell the SIM card. Registration can only be done by phone or online. Recharge vouchers are only sold at Müller (drug stores), ProMarkt and KOMET (both electronics retailers). There are reports on German forums, that regular O2 "Loop Up" vouchers, which are sold nearly everywhere (supermarktes, gasstations, kiosks), work for Fonic, too, but I can't confirm that since I haven't tried those yet.

Also be aware, that the dayflat-tariff (€ 2,50/day) and the volume-based tariff (€ 0,24/MB) can not be used simultaneously. When you buy the Fonic SIM volume-based billing will be active. If you want to switch to the dayflat-tariff, you'll need to call customer care and ask them to switch your tariff. Then you'll be charged € 2,50 for each day you access the web. If you want to go back to volume-based billing, you need to call customer care again.