[Q] simlock.ta - relation with Mobile simlocking ?? topic

Hello everyone,

I am looking for sim unlock on my new Xperia Z1 for free, for 7-8 days now... Nothing found ! No free way to do. :crying:

Then I saw some threads speaking about this file : simlock.ta. And then I was thinking "And if only this file may sim unlock my device ??"

So I would like to know:
What's this file ? And what should it do on my phone ?

Then... If I modify this file, can I Unlock my Xperia Z1 ? (locked SFR - France...)

I think understand that, if simlock.ta is deleted, there is no way to use network from any carrier. But, what about Editing simlock.ta ?