sorry for late reply, first you have to downgrade your device with lowest version of android write default efs you will get 0049 IMEI ,
then repair your original IMEI that is all. phone must be rooted first downgrade ,
then root,
then efs.
and at the end repair IMEI.
that is all if after these process didnt work,then its hardware issue. so you have to change base band chip . once changed, it will work 100percent but you need to use tech service, coz only engineers can change baseband IC.
you can also try this octopus method.
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To connect GT-I9300 phone you have to perform the following steps:
1. Disconnect USB cable from phone.
2. Go to Menu->Settings->Developer options.
3. Turn on "USB Debugging" option.
4. When message is appear press "Yes".
5. Connect usb cable to phone.
6. Go to dial window.
7. Enter *#9090# number.
8. Set speed to 115200.
9. Reboot phone.
10. Press "Read Info" in software.
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Platform: Samsung Android
Selected port: COM15
Selected model: GT-I9300
Searching for a phone. Please wait...
Phone found.
Firmware compiled date: Mon Mar 11 17:37:01 KST 2013
Phone SN: 0000000000
Android version: 4.1.2 (JZO54K)
-----------------------------------------------------------------------------------
Platform: Samsung Android
Selected port: COM15
Selected model: GT-I9300
Searching for a phone. Please wait...
Phone found.
Firmware compiled date: Mon Mar 11 17:37:01 KST 2013
Phone SN: 0000000000
Android version: 4.1.2 (JZO54K)
Old IMEI: Unknown
New IMEI: 351869-05-707346-5
Erasing old IMEI. It can take some time. Please wait...
Creating NVM backup
Backup saved as C:\Program Files\Octoplus\Octoplus_Samsung\BACKUP\NVDATA-GT-I9300-07-11-2013_16-59-43-.nvm file
Old IMEI was erased successfully.
Phone will restart now
After phone being rebooted and powered on perform the following steps:
1. Disconnect USB cable.
2. Go to dial window.
3. Enter *#9090# number.
4. Set speed to 115200.
5. Connect phone via UART cable to Box.
Connecting to phone, please wait...
Phone connected successfully
Deactivating MSL...
MSL deactivate successfully
Writing new phone IMEI...
New IMEI successfully written.
Please, restart the phone to apply changes
