I am new to this forum and very new to the iPhone. I just recently purchased an iPhone and I have firmware version 1.1.1./04.01.13_G. Anyhow, I am guessing I need to downgrade to 1.0.2 in order to Unlock my iPhone for T-Mobile, correct? I downloaded the 1.0.2 firmware version needed. Well, I then tried the method where I have to hold down both the home button and power button, etc, etc, etc. Then I am asked to restore which I find the correct file and it then says "extracting files". Here is where I run into the problem. When it says "extracting files", it finishes in less then 10 seconds and then says, could not restore, and error occurred. Meaning, the older version did not install. What am I doing wrong? Please HELP! Thanks in advance.

P.S. - I don't need to activate the iPhone before unlocking, correct?
P.S.S - How do I activate my phone without paying for the AT&T plan?

iPhone8686