[Q] Verizon Nokia Lumia 929 or ICON topic

Ok, I don't see a thread for this question, but I'm sure there could be by this point. Please forgive my ignorance and point me to where and if this thread should be posted. I was given a Verizon based Nokia Lumia. I have been told it is called an Lumia ICON, but when you look at "about" its called a Nokia Lumia 929. In all my searching of XDA, I don't see a thread for either an ICON or the 929. I see lots of refs to a Lumia 920, but not 929. Bottom line, I wanted to unlock this phone for use with my carrier T-Mobile. In speaking to them, they will give me a T-Mobile sim card, but obviously I have to unlock it on my own. Is there a way to "root" this phone like I have done with previous IPhones? Is there a difference between a Lumia 920 and 929? What is that difference? Are the "UNLOCK SIM CHIP" web sites trustworthy at all? Is this the only option I have, to provide my IMEI number to them and hope for any unlock code from their databases? Like I said, I want to unlock/jailbreak this phone for use with my current carrier, but at this point would also be happy with just some basic enlightening of my ignorance. I'm currently using what "about" says is a Lumia 521, but every search I do on this number, anywhere, spits back only 520's. Is the 521 designation just to distinguish what carrier put it out. Is this the numbering system that Nokia/Microsoft uses to tell them apart? If this is all together the wrong place to launch this thread, please just let me know where I should put it. TIA for putting up with my stupidity.