It's a 4-digit number that lets you lock your SIM card to one device. By default, your SIM PIN is the last four digits of your PUK. You can change your SIM PIN through your device settings. So, if you've forgotten your SIM PIN, enter a random 4-digit number, like 0000, until you're asked for your PUK code.
If you don't know what the default SIM PIN is, don't try to guess it. Check your network provider's customer service page or the documents that came with your wireless plan. Or you can contact your network provider. Tap Done.
A new SIM card usually comes with a temporary default PIN of 0123 or 1234.
Your PUK code is the 8 digit number found on either the SIM or the additional SIM packaging. By default, your PIN code is the last 4 digits of your PUK code – but obviously if you've changed your PIN code yourself, this will no longer apply.
Your PUK (Personal Unlocking Key) is an 8-digit code unique to your SIM card. If you don't know your SIM PIN, you can use your PUK code to unlock your mobile and reset your SIM PIN.
Find your PUK on the SIM card pack
If you've still got the little pack that the SIM came in, check on the credit-card sized bit of plastic that the SIM snapped out from. The PUK Code is an eight digit number, and is usually printed on the back.
This is called a SIM PIN (personal identification number). Typically the user would use the GUI of the phone to enable the PIN. Some manufacturers have a default PIN value set with new SIM cards. Numbers such as 0000, 1234, or the last four digit of the cell phone number (MSISDN) are common.
What is my SIM card PIN? The PIN code for your Three SIM card is printed on the delivery slip that comes with your SIM card. Note that you get three tries to enter the PIN, and your phone will be locked if you fail after these tries. If your phone gets locked, you'll then need to contact 3 to get a PUK code.
If you locked your SIM card, you will be prompted to enter the password when you insert that SIM into a new phone. If you know the password, enter it to unlock your SIM. If not, you can unlock the SIM with a PUK (pin unlock key) that comes from your mobile provider.
One of the less obvious substitutes for a SIM card ejector is found in your stapler. If you gently push the stapler's head, a single staple should come out halfway, without having its ends bent. Pull it out gently and use it to eject your SIM card tray.
If I put my SIM card in another phone, will my number be the same? If you insert your SIM card in a new phone, your phone number will stay the same. A SIM card is only associated with one phone number at a time, so it won't change even when you insert it into another phone.
The SIM card on your mobile phone will become locked if you enter an incorrect personal identification number (PIN) three times. You won't be able to use your phone, except for emergency calls. To unlock it you must reset your PIN by entering your SIM card's unique unlock key (also called a PIN unblocking key or PUK).
If unavailable, ensure a SIM card is properly inserted. The default SIM PIN is 1111.
Generally, you need PUK number to unlock SIM when it gets locked. But luckily, there are still ways for you to unlock SIM card without PUK. You can always ask your service provider to help you after confirming your identity. And even if you fail, professional SIM unlock tools are still there to help you.
The PUK (Personal Unblocking Key) code is a code consisting of 8 digits. It is used to unblock your SIM card when you entered 3 times a wrong PIN code.
What Should I Do if My Sim Is Permanently Blocked? If your SIM card is permanently blocked as a result of entering the wrong PUK repeatedly ten times, the only way out is to contact your service provider. Perhaps, they'll need to help you retrieve your line (by linking your phone number to a new SIM card).
Removing the SIM card will disable your ability to make calls, use mobile internet, and send or receive SMS text messages. On an iPhone this isn't always a problem, as you can still connect to Wi-Fi and use it to send iMessages — but at that point, you may as well buy an iPod Touch.
Data that SIM cards contain include user identity, location and phone number, network authorization data, personal security keys, contact lists and stored text messages. SIM cards allow a mobile user to use this data and the features that come with them.
If you don't have a SIM-eject tool, you can use a small paperclip.
If you don't have a paperclip, there are other options. Straightening a staple with flat ends works, as does cutting off the sharp point on a toothpick. Most earrings also have flat tips, so these also work great.