[wolfbln]

Hi. Welcome to the German tariff jungle.

Blau has different tariff lines:
In the "Basic" (also called 9c) line, you can add data-only packages of e.g. 3 or 5 GB.
In the "Smart" line, you have the included voice, text and data.

Both lines can't be mixed. So you can NOT book a data-only pack on a combined smart pack at the same time.

If you are on a smart pack and run out of (high speed) data (>200 MB), you can always add another 200 MB for 3 EUR to avoid being throttled.
You can add data as well on the data-only packages ahead of time on the basic line.

Take care: There have been reports, that you dont get get an SMS before speed will be throttled - but you will notice that anyway.

If you buy the basic line without included voice or text, you will still get these on the default rate 9c per minute for domestic voice (landlines and mobiles) and text. This is also the rate for overuse (in voice and text) on the smart pack.