Knowledge Base Article
I just had this issue a few days ago. Let's just say you entered your SIM pin wrong 3 times. Then after that it goes into PUK lock. If you ever purchase a new phone and they put a new SIM card in. Always ask for the package that the SIM card came in. ( Usually it has the PUK lock on the packaging and the default SIM lock code number in brackets). If not ask the telus sales representative that sold you the phone or SIM card for the PUK lock and the SIM card default code. Write them down and keep these lock codes and default codes in a safe place or lock box. Now there are Usually 2 PUK lock codes given to you in case the first one fails. Crappy thing is you have to double validate the PUK lock and the SIM code twice. Don't panic and pay attention to the prompts carefully. And don't mess up 8 times or you're locked out for good. So for future reference, if you get a new phone or plan with telus especially at a kiosk or Telus center. Always ask for your PUK codes and default SIM lock pin first time around so that future issues don't occur. It happened to me and I almost found out the hard way.
Also you can change your SIM lock pin afterwards to your preference. However if you mess up the password more than 3 times you have to do the PUK process over again and use the default PIN password or lock.