This is working for most of the android who has Cortex chipset processor in their device. I have tried personally in my Intex canvas Aqua Life III smartphone which is Cortex chipset enabled phone and this trick is working for me. let see �How to use Reliance Jio 4G Sim in 3G android mobile phone with cortex chipset processor�. In this Method you have to check your Device is Cortex chipset or not, for check what type of processor you are using install CPU-Z app. You must have atleast 4.4 Kitkat or more latest version to make Jio Sim Working.

Prerequisite

1. CPU-Z
2. Activated Jio Sim

Instruction

1. Install and open the CPU-Z App, Check what type of Chipset You have .
   
2. If you have cortex chipset (Like below Screenshot) follow the Instruction below
3. Now Dail "*#*#4636#*#*" in your Dailpad
4.  It takes you to Engineering or testing or Service mode.
   
5. Now click on the �Phone Information� and Hover to Set Preferred Network type.
   
6. Click that Dropdown a list of Option Shows and select "LTE/GSM/CDMA auto(PRL)".
   
7. Now Turn off your Device and Remove Simcards.
8. Insert Activated Jio Sim in Slot 1 and remains slot 2 empty.
9. Now �Switch ON� your device.
10. Still it shows emergency call in the network.
11. Go to setting>Cellular networks>Network Operator>Search Network.
    
12. Search in Manual you can find "LOOP Mobile 4G", if u didnt find that keep searching until find that before that turn ON Data Connection.
13. Select "LOOP  Mobile 4G" and now you can acess Jio 4G in your 3G.
14. Enjoy your 4G in 3G android Mobile.