iPhone 3G - 3.1.3 - Need to upgrade to 4.x - BB 05.12.01 - Unlock

[sibot]

Hey,
As the topic suggests, I'm on 3.1.3 and BB - 05.12.01, I'm using ultrasn0w to unlock on 3.1.3 but am facing constant signal drops.

I plan to upgrade to 4.2.1 or any other firmware in order to see if that sorts the issue.

I tried upgrading to 4.0.1 but I'm facing constant 3194 error even after modifying the hosts file.

I wanted to know whether I can safely upgrade to 4.2.1 and unlock using ultrasn0w or would I have to use the iPad BB to do so?

Thanks in advance,
Sibot

[iYeow]

Put iphone into pwned dfu and restore to custom firmware of 4.2.1 to preserve your bb for unlock with ultra snow .