Order a free SIM Activate your 48 SIM
Are you sure that you set it up properly?
Did you follow these instructions to the letter?
Try dialing your number prefixed by 5 after the 08x prefix and see what happens - it should go to your voicemail if it's enabled properly - e.g.:
089 5 1234567
If it doesn't then it hasn't been set up properly.
Hope this helps.