Hello everybody.

I newbie as member but because was never necessary register me here before until tonight

I have a trouble betwen hands with a iPhone 4, model MC603B and iOS 4.3.5, the iPhone is released but the carrier is locked.

The iPhone have the cydia installed but all SIM that i prove show the same trouble

The signal bar is of a line, I can not make calls using the telephone and after of time the signal bar change to No Signal

I was reading and searching in google and seems be that the solution is install ultraSnow from cydia

Here come 2 questions

ultraSnow is compatible with the iPhone 4 using a baseband 01.59.0 and the baseband on my iPhone 4 is 04.10.01

If I apply the ultraSnow, What problems I can have?

If restore the iPhone to iOS 5 and apply the jailbreak, Could be a solution or aniwat I am forced to use the ultraSnow?

Thanks in advanced

Postdata: for get the iPhone working, I was forced to apply the jailbreak because the iPhone was hired with ORANGE UK and of another way i never could reach the initial screen