[inquisitor]

Originally Posted by mgol

I thought it was your thread here Germany - Tchibo - Prepaid Wireless Internet Access, from which I copied the above USSD commands.

Yes, I'm the author of that wiki page.

Anyway, returning to my question is it possible to activate "Internet Flatrate XL" by using USSD commands in MDMA (if yes, what are the commands) ?

I described the USSD-based order process in detail on the first page of this thread.

Regarding your suggested text message, I must to confess that I have no idea of how to send it. Sorry, you only tought me to send USSD commands in MDMA and to receive SMS by using Mobile Partner. Is sending text message just the other way around ?

Just start Mobile Partner, click the "Text" button and below you'll see a new row of symbols, where the frist one (a blue enevlope) stands for creating a new text message. Hit that, enter phone number (7777) and text (START DATENFLAT) and finally click "Send" to submit it.