What Is a PUK (Personal Unblocking Key)?
What does PUK mean?
PUK stands for Personal Unblocking Key. It is a security code used to unlock your SIM card after you have entered your SIM PIN incorrectly too many times.
In short: PIN locks the SIM – PUK unlocks it again.
The PUK is always 8 digits long and is permanently linked to your SIM card. It cannot be changed.
16.01.2026 | Reading time: 3 minutes
When do I need a PUK?
You need your PUK if:
- you entered the wrong SIM PIN 3 times
- your phone shows “SIM locked” or “Enter PUK”
- you inserted your SIM into another phone and forgot the PIN
Without the correct PUK, you cannot make calls, send texts, or use mobile data.
What happens if I enter the wrong code?
After three incorrect PIN attempts, the SIM card will be locked and a PUK code will be required to unlock it. If the PUK code is entered incorrectly four times, the SIM card will become permanently blocked.
A permanently blocked SIM card cannot be unlocked and must be replaced.
Where can I find my PUK?
You can find your PUK:
- on the original SIM card holder
- in your yallo online account under SIM details
- in the yallo app (depending on view)
If you no longer have access:
- contact yallo customer service
- after identity verification, you can request a SIM replacement
What happens after I enter the PUK?
After entering the correct PUK, your phone will ask you to:
- set a new SIM PIN
- confirm the new PIN
Your SIM will then work normally again.
Interesting facts about the PUK
- The PUK is unique to each SIM, not to your contract
- eSIMs also have a PUK stored digitally in your account
- A blocked PUK cannot be reset for security reasons
- You may need the PUK even when abroad
- Replacing the SIM is often the fastest solution if the PUK is blocked
Quick Tips
- Store your PUK separately from your phone
- Do not throw away the SIM card holder
- Do not guess your PIN
- If the PUK is blocked, order a new SIM immediately
