[XDA]有關IMEI喪失 - Android 台灣中文網

I have a 0049 or 0000 IMEI. Why?

This means your phone cannot read your IMEI. There are 2 main reasons for this.

1) /efs is corrupt.

Whenever you flash a ROM, be that a custom ROM via a custom recovery or an official ROM via Odin, you risk corrupting your /efs partition and losing your IMEI.

There are 3 main steps to take to try to resolve this
Restore your EFS from a backup - A logical first step
No backup? Reflash the latest stock ROM using Odin*
Send the device for repair**

*Ultima rom users (prior to v15), first reflash the rom, choosing a non-stock kernel during the aroma install wizard first. Boefla is a good choice to test.

** a couple with "cannot mount /efs" errors have fixed their device by flashing ics. If you know you haven"t got a VTU00M eMMC firmware 0xf1 - go for it. However for those of you who don"t know, this would be extremely dangerous. You could get SDS so I do not recommend this action. If you are foolish enough to try it, flash 4.1.2 immediately afterwards.

2) /efs partition format changed

A quick note before going forward... when looking at a ROM build number, the last 3 characters mean Year, Month, Revision. Let"s take XXEMG4 for example. M = 2013, G = July, 4 = revision 4. See "Other" section at the end of this post for more info

From July 2013 (XXEMG4) onwards, official Samsung ROMs change the format of your EFS Directory/Partition. Let"s say these ROMs change from EFS v1 to EFS v2. Only basebands from July 2013 (MG2) onwards can read EFS v2.

Quick info rules:
EFS v2 Basebands can read EFS v2 and EFS v1
EFS v1 basebands CANNOT read EFS v2, ONLY EFS v1

This means if you have flashed an official ROM (or custom ROM based on official) From July 2013 (MG* or newer), you are now in a situation whereby only an EFS v2 baseband (MG* or newer) can read the IMEI in /EFS.

If you have ever flashed XXEMG* (or newer) ROM, to keep your IMEI working, you must:
Stay with the EFS v2 basebands (MG* or newer). You may flash other ROMs but must return to the MG* (or newer) baseband
Restore your EFS backup (taken before XXEMG* or newer ROM install) to use older (EFS v1) basebands. EFS backup must be an EFSv1 backup to use an EFS v1 baseband
If the above don"t work, consider sending for repair...

*Ultima rom users (prior to v15), first reflash the rom, choosing a non-stock kernel during the aroma install wizard first. Boefla is a good choice to test.

Please note, it is flashing the ROM that alters EFS format, not the basebands themselves. You can flash the MG* or newer basebands safely on their own and return to an older baseband without issue.

You can download an EFS v2 baseband (CWM) flashable package HERE - updated to MJ3 by @maatsby
Aroma installer, choose between MG2, MG4, MH1 and MJ3 basebands
Basebands alone do not alter efs format
Backs up EFS in an uncompressed format (Use Root Explorer to restore)
Does NOT include RIL, works on AOSP and Sammy

For discussion of the efs format issue, see this thread.