Oh, then they made this new.
My Aldi-SIM did not require to type in any PIN. It just sent a Welcome message after the first call. Yes, all E-Plus-Based SIM-Cards get activated after the first call. There was a nice bug some time ago that you could use GPRS free of charge if you used it before activating the card. apperatnly this bug is now fixed and you cant use GPRS on a non-activated card anymore
Balance check is *100# (comes as flash-sms) or dial 1155 and press 1 (in german)
Chris