This example is for the Samsung SCH-R720 (Vitality, Metro PCS, Generic etc.) but the same methodology can probably be applied across most android brands/ models. If your MEID/ESN is incorrect/ corrupt you may experience one or more of the following: * You are receiving MEID/ESN error messages * Your OS may also not work correctly i.e. screen doesnt turn off, lock screen doesnt work, certains apps and widgets may force close themselves or cause the launcher to force close. Different phones may behave in different ways. * The following or similar text is displayed on your launcher screen (attached screenshot1, screenshot2) CHANNEL : 30600 SIO MODE : U1_DM USB2_NULL S/W Version : SCH-R720.**** Baseband Ver: S:R720.00 x.**** H/W Version : H:R720.00 x.* * Disruption is caused to your cell/ data/ mms service. You can also type *#06# in your dialer to see your MEID information. They should be 14 digits long. If its mainly full of zeros its probably corrupt (mine was B000000). A hex and decimal MEID number can also be seen under your phones settings, about phone, status menu. Ignore the 0x or 0H at the start of hex meid number, this simply means that a hex number will follow. If it doesnt match the hex MEID on the label behind your battery then its definately corrupt. The most likely cause of this problem is a bad flash and may void your warranty. To restore it do the following (Windows example only, no Mac support) 1. If you havent already, Download and Install (Samsung) USB drivers for your phone from your phone manufacturers (their) website. Samsung SCH-R720 MetroPCs Drivers Support - More Cell Phone Providers SCH-R720 | Samsung Cell Phones Samsung SCH-R720 Cricket Drivers Support - More Cell Phone Providers SCH-R720 | Samsung Cell Phones Samsung SCH-R720 Generic Drivers Support - More Cell Phone Providers SCH-R720 | Samsung Cell Phones (optional: if you havent already and wish to take an extra precaution its advised that you backup your phone setting data before processind just in case you have a bad write. http://www.getandroidfree.com/basic/android-tips/backup-the-phone-configuration-using-qpst/) 2. Download and Install CDMA Tool DFS, a free demo version (which is sufficient to do the restore) can be obtained from here. I am not sure if there is a time restriction as I got some key errors after a few days even though it was a demo, so its best to crack on with it as soon as youve installed it CDMA Tool. DFS software. www.cdmatool.com. If you dont have .net 4 or higher already installed youll be asked to download and install this from Microsoft which you should do when prompted. If you have problems you can download it from here (older versions of DFS appear to use older versions of .net). Online Installer Download: Microsoft .NET Framework 4 (Web Installer) - Microsoft Download Center - Download Details A full installation for offline computers can be downloaded from here. Download: Microsoft .NET Framework 4 (Standalone Installer) - Microsoft Download Center - Download Details Either way make sure you reboot after this installation and if necessary complete your CDMA Tool DFS installation. 3. Once both are installed, open up my computer on your desktop and make a visual note of the drive letters, connect your phone to the computer. At this point a new drive letter should appear. Next either right click my computer on your desktop, select properties or click your start button, select control panel and select system. Then select the hardware tab, select Device Manager, double click modems, a SAMSUNG Android USB Modem (or your model of phone) should be listed. 4. Run CDMA Tool DFS, close the account page. Select ports, then right click Samsung Android USB Diagnostic Serial Port and select add/remove port (a green circle appears next to it when its attempting to connect or is connected). Check to see if there is an entry (with your devices details) in the bottom window. Its unlikely to appear there at this point. If it is you can proceed to step 5, otherwise follow the troubleshooting guide first. TROUBLESHOOTING NOTE: throughout this whole process do not turn on USB Storage or ensure it is turned off. i.e. do not select connect to copy files option in the notifications window. The first thing you need to do is turn on USB debugging (Incidentally for the Samsung R720 and probably many other models you can leave usb debugging turned off). This can be completed on your phone by going to Settings/Application/Development/ check USB debugging and then click ok. Go back and see if your device appears, you may have to remove and add the port again. If so then proceed to step 5. If not, then youre also going to have to open up your phones debug port or equivalent. You should be able to access the debug menu by dialing ##DEBUG# or ##33284#. on your phones dialpad. If not then youll need to do your own research on the net or via your provider to find out what this is for your phone. SPC/MSL Code For the Samsung R720 (and probably most phones) youll have to enter your SPC/ MSL code number next, its probabaly 000000, if not then try 111111, 333333, 999999 etc. Also try your SPC/ MSL code supplied from the whiterabbit link in the OBTAINING YOUR FULL ESN/ MEID INFORMATION section below. Once your in rememeber this number as youll need this in CDMA DFS Tool later. Next scroll down to port map and select HFK,DIAG and click ok (the menus and options will probably differ by make/ model). Once done your device should appear in the bottom window of CDMA Tool DFS, remember you may have to remove and add the port again. 5. Double click this new entry. Your phones information should populate the boxes in the Equipment tab, if not something is wrong. NOTE: After a day or two I got a product key error even though its a demo and couldnt get any phone info but could read ESN/MEID information (not sure about write) so you could probably finish the job without correcting it. I used another computer to complete it. Next you need to enter your SPC/ MSL information in and connect to the device. Its located in a box in the top left hand corner of the app with a icon/ SPC next to it. Its defaulted to 000000, if you dont know yours please read the SPC/MSL code section above about the SPC/ MSL code for your device. Once inputted push the SPC button Check the log window to see if its connected correctly it will say Device Unlocked, while your in there select diagnostic under message level. Click on the Programming tab, under the ESN area click read, repeat the same for MEID, either no information or incorrect information will appear. Your Metro PSC will also be displayed in the SPC section. OBTAINING YOUR FULL ESN/MEID INFORMATION Before continuing youll need to obtain your full ESN/ MEID information. You should have already written this down earlier, if not some of this information should be located on the label behind your phones battery. You should obtain at least some of your MEID information from here as you can't continue without it. You need to go to the following two sites and enter/ calculate your MEID information. CDG : Devices : ESN, MEID and EUIMID Calculator This will provide you with MEID/ ESN in both HEX and DEC along with your Check Digit (CD) Number. Youll need to remove the spaces from the results before putting them into CDMA DFS Tool. This site does not provide your SPC/ MSL number which is calculated automatically anyhow by CDMA Tool DFS. This site provides the same information along with SPC/ MSL but excluding check digit (CD) info. The SPC/ MSL information may be useful if youre having problems connecting to your phone or accessing its debug menus (in troubleshooting and step 5). android - whiterabbit.org Scroll down to the android section and type in either your HEX or DEC MEID not ESN number, select calculate. You can also use this app from the app store. https://play.google.com/store/apps/details?id=com.splicedmedia.android.meidconverter&hl=en but if you want to add your check digit (CD) number which I dont believe you need to do then youll still need to go to the CDG website to obtain it. 6. Remove any old or incorrect data from the ESN/MEID boxes in CDMA Tool DFS, enter your new information obtained from the websites, you only need to enter either hex or dec, the other is caluclated automatically, double check all entered and calculated info matches that provided by the website and the info obtained from behind the battery. Also enter your Check Digit (CD) information in the MEID area (if appropriate). Then click write for both ESN and MEID. You may have to do this a few times for it to write successfully, check the log window in CDMA TOOL DFS, it will say if its successful or not. A good way to test to see if it was successful is to remove the info and click read, all the newly entered info should reappear. NOTE: Dont change anything else, i.e. IMEI is for GSM phones and SPC/ MSL should be calculated automatically. Reboot your phone, check your new info by dialling *#06# again and looking under settings, about phone, status in your phones menus (again ignore any 0x or 0H at the start of meid numbers). If not then repeat the writing process again from Step 4. After youve finished remember to reverse some steps if applicable. 7. Turn off usb debugging 8. Goto your debug menu and return it to its orginal setting (just in case you return/ sell your phone). (optional: You may wish to backup your phone setting data again, should the problem repeat itself at least its just a simple restore. If you did one before completing this restore, keep the old one too - dont overwrite it, just in case you had a bad write. http://www.getandroidfree.com/basic/android-tips/backup-the-phone-configuration-using-qpst/) This article is just to restore your corrupted MEID/ESN numbers in order to remove error messages and get your Android OS functioning correctly again. It may also revalidate your warranty. Please remember you may need to do other things to get it back on the network. I can only answer questions about Samsung SCH-R720 phones that are not network connected. If you want to add some additional instructions please post and ill add them. You may be able to use CDMA Tool DFS for GSM phones as there is an option there for IMEI. Some useful links SPC and MSL codes Master Subsidy Lock (MSL) Codes MEID Information Mobile Equipment IDentifiers (MEID) | Telecommunications Industry Association Another app worth consider to do with the job with is QPST. A post using these aps for another device is listed here. http://androidforums.com/optimus-m-...-restore-service-if-youve-lost-your-meid.html NOTE: If the problem arose after flashing your phone with a rom etc, next time use a different USB port i.e. a back port instead of front one etc.