3g unlock issue after having 4.1

[entronp]

Second time I have seen this. Someone put 4.1 on their 3g, I downgraded it to 3.13 (also tried 4.0) jb and unlocked, everything went great. BUT, it wont accept tmobile or att sim card! Just says "searching" forever....anyone dealt with this before.

 

[ducky]

once upgraded to 4.1 the baseband is updated and renders all (and possibly future) unlocks in-effective.

i think the latest version of tinyumbrella has a feature built in that will preserve the unlockable baseband now.

 

[entronp]

Thats what I feared....so is it possible to determine that it is not unlockable if the phone is downgraded to 3.1.3 or something? Worried that I might buy a phone and find out it used to have 4.1

 

[ducky]

i suppose you'd just have to try putting a sim card in from a non sanctioned carrier to be 100% certain it's unlocked.

 

[entronp]

i suppose you'd just have to try putting a sim card in from a non sanctioned carrier to be 100% certain it's unlocked.

yeah but what if they say its not unlocked? So, the modem firmware doesnt give any hints right? Kinda scary if you want to buy a phone....I thought 3g's were unlockable no matter what...this sux

 

[Jayel]

Hey Guys, Total newb but recently got my friend's old iphone 3G which she hadnt upgraded the firmware or unlocked it. I am currently in Taiwan and I thought, "well, before I unlock it, I should update the firmware and then unlock it." So I recently updated the firmware from 3 something to 4.1, now am I screwed? From what I am reading here I can not unlock or jailbreak.

At the very least, I want to unlock the phone so that I can use it on the carrier system here, Taiwan Mobile. What are my options, if any?
Please help!!!!

 

[entronp]

you can jailbreak but no unlock...sell it.

 

[myzhi]

yeah but what if they say its not unlocked? So, the modem firmware doesnt give any hints right? Kinda scary if you want to buy a phone....I thought 3g's were unlockable no matter what...this sux

Modern firmware is the baseband which can never be downgrade, only exception are some few early 3G Iphone using Fuzzyband. Using the baseband number you can tell if ultrasn0w, app you use to unlock, is compatible or not.

For example, if you update to firmware 4.1 => baseband 5.14.02, ultrasn0w won't work because it hasn't been updated for that baseband. And, if you need Ultrasn0w to unlock, you will loose it whenever you change the firmware. Thus, you need to be careful which firmware => baseband you change to.