IMPORTANT INFORMATION

[Annarit_3052892]

FOR YOUR INFORMATION, WHEN YOU CHANGE A SIM FROM GADGET TO GADGET, IT SEEMS TO RUIN  THE SIM. AND JUSUALLY BLOCKS SCREEN, YOU HAVE TO ASK FOR PUK.

[MSF]

@Annarit_3052892 That is not the case unless you handle a sim very roughly. in which case you will damage it.

The PUK is related to the wrong unlock code being entered too many times as @SmartyTrousers says.

If you feel that the sim is not good, why don't you order a Replacement Sim in your Account Dashboard?

[WelshPaul]

Simply turn off the SIM pin or don’t forget it next time!

You’re only asked to enter a PUK code if you insert an incorrect SIM pin three times. 

[SmartyTrousers]

@Annarit_3052892 That's not true. I've moved SIMs between devices many times and never had an issue.

Also, a PUK is used to unlock a SIM if you have entered the SIM's PIN incorrectly too many times.