All plan.com SIM cards are supplied without a PIN code.
If you've forgotten your PIN and need to reset it, you'll need a PUK code, to begin the reset process.
To view your PUK code, go to:
CONTROLS > DEVICE > PUK CODES > DEVICE CONTROLS: PUK CODES
Use PUK1 to reset your PIN
Use PUK2 if you mis-typed PUK1 three times in a row.
If you mis-type PUK2 ten times, your SIM will locked, permanently.