Are you sure, that you do have a BLAU-SIM and not a BLAUWORLD-SIM???
BLAUWORLD only offers a "flatrate" for landlines. Both Simcards are labeled with blau.de (!!) and it is shown "BLAU" on your phone!
http://www.blauworld.de/app?page=wor...e&service=page
If you are not sure:
1. Check your balance (*100#)
2. Send yourself a SMS
3. Check your balance again.
If the diffenence is 9 ct, it is BLAU, if it is 15 ct it is BLAUWORLD
or
Dial 9911 (if not in English dial 3 - 9 - 2). When you are able to deactivate your voicemail (menue 3 - 2 - 8 ), you got BLAU, otherwise it's BLAUWORLD. Voicemail access is free - on BLAU, but 15 ct / Min at BLAUWORLD
http://www.blau.de/cms/blaude/documents/mailbox.pdf