Usually Invalid IMEI error occurs after you flash your MediaTek device. No need to worry as there is a simple fix for this issue. No need of root privileges on either method.
Method 1: (Works even if your phone a single error of Invalid IMEI or both if you have a dual sim)
1. Open dialpad and input *#06# (If a single sim is working you can see an IMEI and another is invalid, you can find invalid IMEI under battery of your phone)
2. Copy IMEI number.
3. If no sim is working you can find those numbers just below your phone battery.
4. Open mobile uncle, click engineer mode and chose android or mtk.
5. Go to connectivity, CDS Information, then radio information and chose the sim that isn’t working, either one or two.
6. For sim 1 press phone 1, Click on AT+ on the top and type these AT+EGMR=1,7,”XXXXXXXXXXXXXXX”….. Here “XX…..X” is your IMEI number. Type it (make sure its in quotes). Now click send then reboot.
7. If invalid sim is sim 2 then click phone 2 and type AT+EGMR=1,10,”XXXXXXXXXXXXXXX” , click send then reboot.
Dial “* # * # 3646633 # * # * 2- then follow that path –> CDS info –> Radio info –> Phone1 (for the first imei) 3- at the top there is a command line which begins “AT+” just type there “AT +EGMR=1,7,”IMEI_1? (instead of IMEI_1 put your first imei number) 4- hit send command 5-if you done just reboot the phone, if you change the second imei go to step 2 and select “Phone2? 6-and enter the code “AT +EGMR=1,10,”IMEI_2? (instead of IMEI_2 put your second imei number) hit send command 7-reboot 8-Dail ” *#06#” Check Imei(onlyshow the first one.
Sometimes when you factory reset your android phone you will not get signal of your SIM card or else it will show as only emergency calls. It may occur due to invalid IMEI problem in your phone. To check if you have invalid IMEI problem in your phone you may dial *#06#. A Popup Box Will Be Shown in Which if your IMEI will be present the number will be shown and if not present it will show as Invalid IMEI. Invalid IMEI problem may also be faced after installing a new rom or after upgrading your system. In this article I will teach you how to fix invalid IMEI problem on custom ROM rooted android phones.