Mobile data in Germany? (but D1/D2 only)

[inquisitor]

Originally Posted by fuxoft

a) Can I buy callYa 5/15 SIM card in any Vodafone shop, without being a German citizen, and use it immediately?

Yes, but it would be cheaper to buy a Fonic SIM, since with Vodafone you would need to buy a 7-day-session for € 9.95, while Fonic will charge only € 2.50/day, so for your stay it would only cost € 7.50.
Further with Fonic you can call home to the Czech Republic and to the rest of the EU for just € 0.09/min (landlines) or € 0.29/min (mobiles). Details on Fonic are available at Germany - Fonic - Prepaid Wireless Internet Access
Please be aware, that with Fonic you will need to call customer care and ask them to switch your data tariff to "Tagesflat".

b) Does the default callYa price include some amount of credit or not? Can I top up directly in the store, while buying the card?

At least those prepaid SIMs offered online come with € 10 of credit. Of course you can add credit in any Vodafone shop or buy vouchers nearly everywhere. For details see Germany - Vodafone Web Sessions - Prepaid Wireless Internet Access

c) Are all INCOMING calls to this SIM free while I use it in Germany?

Incoming calls are always free with European operators, as long as you stay in the country your SIM is from.

[fuxoft]

Originally Posted by inquisitor

Yes, but it would be cheaper to buy a Fonic SIM, since with Vodafone you would need to buy a 7-day-session for € 9.95, while Fonic will charge only € 2.50/day, so for your stay it would only cost € 7.50.
Further with Fonic you can call home to the Czech Republic and to the rest of the EU for just € 0.09/min (landlines) or € 0.29/min (mobiles). Details on Fonic are available at Germany - Fonic - Prepaid Wireless Internet Access
Please be aware, that with Fonic you will need to call customer care and ask them to switch your data tariff to "Tagesflat".

Thank you, I didn't know about Fonic!

Again, the call-rates are non-issue because I'll really only be using Internet. The more important question is: What is the signal quality of Vodafone vs. Fonic? I'll spend most of those 3 days on the highway or in smaller cities. I don't need FAST internet, I need RELIABLE internet.

Also, I need to use the card as soon as I cross the border from the Czech Republic and buy it in the first larger German city (Dresden, probably). How fast is "switching to Tagesflat"? Don't I have to wait several hours for it to take effect?

[inquisitor]

Originally Posted by fuxoft

Again, the call-rates are non-issue because I'll really only be using Internet.

I understood that, but I mentioned those call rates as an extra advantage beyond the cheaper data tariff.

The more important question is: What is the signal quality of Vodafone vs. Fonic? I'll spend most of those 3 days on the highway or in smaller cities. I don't need FAST internet, I need RELIABLE internet.

O2 also cover nearly 100% of the country and they have EDGE (up to 200 KBit/s) on their whole network, so you should always get a signal and reliable data connections, but Vodafone of course provide better 3G coverage as you can see from this map :

Also, I need to use the card as soon as I cross the border from the Czech Republic and buy it in the first larger German city (Dresden, probably). How fast is "switching to Tagesflat"? Don't I have to wait several hours for it to take effect?

No problem. All Fonic retailers are listed in my earlier posting. E.g. Fonic is sold at Lidl supermarkets and it can be activated immediately by phone, too.
The switch to the "Tagesflat" is carried out while you are still on the phone with customer care. It's about seconds and you will be notified of the switch by SMS.