[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] zeesubalpha:
TO MINIMIZE THE CHANCE YOU LOSE YOUR IMEI, BE SURE AND ROOT/CWM USING THIS METHOD:

http://xdaforums.com/showthread.php?t=1739426

AND ONLY FLASH ROMS INTENDED FOR USE ON YOUR MODEL

**UPDATED 7/16/12**

questions we are trying to answer:

- what versions of clockworkmod, if any, are prone to causing IMEI problems?

- what rooting methods, if any, are prone to causing IMEI problems?

- what ROMs are causing imei issues, and on which models? is the rooting/cwm method related?

- where is the IMEI stored on the phone, and most importantly

- is it possible to back it up, and restore it once corrupt?

RESTORING AN /EFS BACKUP DOES NOT APPEAR TO RESTORE AN IMEI AT THIS TIME.

TO BE SAFE, USE THIS GREAT SCRIPT BROUGHT TO YOU BY DROTHENBERGER AND SFERNANDEZ:

http://xdaforums.com/showpost.php?p=28528532&postcount=38

You will need Cygwin (http://www.cygwin.com/) for the script.

Original post by sfernandez detailing the partitions: http://xdaforums.com/showpost.php?p=28519596&postcount=39

IF YOU HAVE THIS ISSUE, PLEASE FILL THIS OUT AND POST. THANKS PINOYMUTT:

1. CARRIER VERSION:

(ATT, TMo, Sprint, Verizon, Bell, etc.)

2. ROOT METHOD:

Exact method you used to root, please link to the thread if possible

3. CWM INSTALLATION METHOD:

Again, please be specific. Examples include the ADB/DD method, flashing via ODIN, etc.

4. CWM VERSION:

Which CWM are you using -- the Sprint version or one of the Clockwork ones?

5. ROM(s) FLASHED:

Did you flash any ROMs after the above, and how did you flash it?

6. WHEN DID YOU FIRST NOTICE IMEI WAS GONE?:

It helps if you know which step may have caused the issue

7. OTHER NOTES:

RULES

1. Please READ THE ENTIRE THREAD BEFORE POSTING. There is way too much info in here for me to summarize.

2. ALWAYS READ THE THREAD BEFORE POSTING

3. If your phone is working properly and your IMEI is intact, and the method you used to root and install CWM has already been detailed by another member,

WE DO NOT NEED TO KNOW IT ALSO WORKED FOR YOU. LET'S TRY AND KEEP THE THREAD CLUTTER DOWN

4. No arguing or bickering over stupid crap. Keep that to PMs.

5. READ THE THREAD BEFORE POSTING. THANK YOU.

original post:

If you have flashed a new ROM on your phone recently and have found difficulty or impossibility in getting cellular or data service, chances are you have corrupted or deleted the file that stores your IMEI. i'll try to answer a couple of common questions and detail methods i used, and why i think they failed

What is an IMEI?

your network identifies your phone by its IMEI. once i had "lost" mine, AT&T's network would not provide service to my device, even after getting a new sim card.

How can I check if mine is corrupted?

your IMEI is a 15-digit number under your battery. dialing *#06# should display the same number under your battery. if you get a different number or something like 0 / 00, you have corrupted your IMEI.

Changing the APNs

marginally effective at best. your phone is not registering on AT&T's network as a device it should send data to, so it doesn't matter what APN you use.

flashing to stock rom

did not work for me. probably because this probably doesn't effect the /efs partition, where the IMEI is stored.

use CWM / nandroid restore

from what I can tell, a standard backup does not back up the EFS partition. you need to use something like EFS pro to backup your /efs directory (where the IMEI is stored). restoring my phone to a previously stable and working save did not restore my IMEI

editing nv_data.bin

no one has been able to find this file on the SGH-i747

using a terminal / AT interface

it looks like the IMEI is encrypted and causes a stack overflow when you try to query it. notice how i can query my IMSI (edited) fine, but querying the IMEI causes a stack overflow. pic:

http://imgur.com/uZxZL

i probably tried a few more things i can't think of right now. moral of the story is... approach unstable roms with caution, and BACK UP YOUR EFS PARTITION!!!

anyone had any luck restoring a busted IMEI? :highfive: