A message will appear on your phone saying your PUK is locked. At this point, you will need to enter your PUK code or you won’t be able to access the phone. If you also enter the PUK code wrong 3 times, the SIM card will be locked. If you enter the wrong PUK code 10 times or more, then you will need a new SIM card. Some phones call this a PUC code instead, but it’s the same thing. The code is 8 digits long. [2] X Research source [3] X Research source

There are a few other reasons why you might want to know your PUK code; the most common is if you’re moving from one network service provider to another but want to keep the same mobile number. Working out your PUK code is normally very simple although it can vary depending on who your current provider is. Make sure you write it down somewhere so that you don’t forget it once you get it, and also be aware that some service providers limit the length of time the PUK code will be active. A PUK is a second level of security on a SIM card. The PUK code is unique to the SIM inside the phone and not the phone itself. The PUK is kept by the network operator.

Look at the box that your SIM card came in, and the PUK code should be there on the box or label. You could also call the retailer you have purchased the phone from if you can’t find this code, and they should be able to assist

If you cannot find it, give your mobile network a call, and customer support will be able to give you the PUK code or generate a new one after you have answered some security questions. [4] X Research source The network provider is going to ask you to prove your identity. Sometimes, this entails providing your date of birth and address. You won’t be able to get the PUK code if you can’t prove that you own the phone. You might be asked for the SIM card code from its packaging too. [5] X Research source

Log in to your mobile phone account on your computer and look for a PUK code section on your account page. Where this appears will vary among network providers. For AT&T Wireless, you log into the AT&T online account. Select “wireless” from the “myAT&T” tab at the top of the page. Select “phone/device. ” Select: “Unblock Sim card. ” A new page will open that provides your PUK card. [7] X Research source Some prepaid phones also use PUK codes and will provide them to you online if you know the mobile number and the name and date of birth of the account holder. [8] X Research source If you don’t already have an online account, it’s usually easy to create one if you have your mobile number and basic information to prove your identity.

Follow the instructions on the phone to complete the process. Different mobile phones will have different steps, but most will inform you they’ve locked the phone down and that you need to type in the PUK code.

After you have done so, your cell phone should be unlocked, and you will be able to use it again. Some phone users must enter *05 before entering the PUK code. Then, enter the 8-digit PUK card and hit enter. Nexus One users should type in the *05, their PUK number, *, their new PIN number, *, their new PIN number again, #. [9] X Research source