Sony Ericsson G30 - Manual (Page 27)

Advanced Features
Fixed Wireless Terminal: G30 and G35 models 27
To Unblock your SIM Card
To unblock your SIM card, you need to enter your PUK (Personal
Unblocking Key), which can be supplied by your network operator.
The procedure to enter the PUK is exactly the same as for entering the
PIN.
Note: If you enter the wrong PUK ten times in a row, your card will
be permanently blocked. If this happens, you should contact your
network operator.
In order to unblock your SIM card and change the PIN at the same time,
please dial the following sequence:
**05*PUK*NEW_PIN*NEW_PIN#
Note: If instead of hearing 3 beeps you can hear a deep tone, this
means that there has been an error in the activation or the
deactivation.