SMS Notifications Error: ‘Sms error 'Device not ready' (16013).’

Got this error today at a customers site. SMS was configured as stated in this blog posting. But nothing got out. These two errors were shown in the Console:

1. Failed to send notification. Notification subsystem failed to send notification over 'SMS' protocol to 'xxxxxxxxxxxxxxxxx'.’
   
   
   
2. Failed to send notification using server/device. Notification subsystem failed to send notification using device/server 'Standard  9600 bps Modem' over 'SMS' protocol to 'xxxxxxxxxxxxxxxxxxxx'.
   

All was checked. The modem worked just great. The diagnostics returned good data, the modem was properly recognized.

So time to check out the hardware. As it turned out, the SIM contained a PIN and was configured in such a way that it asked for it before it became fully operational. After removing the PIN challenge all worked just fine.