Does unlock code have an expiration? What sim to use?

[nomoore]

I just got unlock codes from tmobile for my 2 LUMIA 635 phones. I didn't realize you need a third party sim to unlock. So I have a couple of questions.

1.) Do the unlock codes expire? If so how long do I have to get a sim to unlock with?

2.) I read somewhere that you must be in the service area for the sim you are unlocking with. Does that sim need to be activated too? So could I buy something like a $0.99 straight talk sim and use that to unlock without buying a bunch of minutes?

 

[xandros9]

1. I do not believe the codes will ever expire.

2. I don't think it needs to be activated or in service, I think it just needs to be a different SIM. I would probably try to borrow a SIM from a friend on a different carrier to use or get a cheapo unactivated ST or T-Mo SIM.

 

[RumoredNow]

1) Nothing you do should ever reverse the unlock... If you took it for service and they replaced a certain chip it might revert back...

2) You don't even need a SIM card. Open Phone and on the dialer pad type ##7820# you don't even have to press call. It will automatically take you to a screen with a SIM card and a Padlock icon. There is a field there to enter your unlock code and press the check mark. Your icon will change from locked to unlocked. Done.