Tell me the iPhone 3gs unlock algorithm

Question

iPhone

They handed me an iPhone 3gs, with which, according to indirect data, a firmware update was made. Apparently up to 4.2

I do not know the background of the iPhone, but it seems that they did not buy it in Russia. Maybe the USA.

Now the “connect me to iTunes” logo flaunts on the screen and the IMEI and ICCID are displayed.
When connecting to iTunes, it requires you to insert the original sim card.

What can be done and in what order?
I even have an AT&T microsim card, but it is a microsim card.

PS I do not know how to find out the version of the modem and everything else.

Answer 1

1. Download redsn0w 0.9.6b4 for jailbreak
2. Download ultrasn0w from Cydia (already on a jailbroken device), for unlock .
3. Jumping, dancing and shouting for joy (optional)

Answer 2

somewhere on www.iphones.ru there was a detailed instruction on jailbreak.
And somewhere in the same place there was a video of how a person set himself 4.2, made a jailbreak and his iPhone began to be terribly buggy.
So install or not install a new version of iOS at your own peril and risk.
I'd rather use 4.1 for now, jailbreak it and it works great.