Anyone using Jio in 3G phone?

[fadingstar]

Hello guys,
Sorry if this is in wrong section.
One of my friend using Jio 4G sim in 3G handset but he wouldn't told how he did?
I tried various guide and also watched and did as some videos showed on YouTube but all in vain.
After requesting my friend on how he did he just gave me a hint that device should be on Kitkat or above versions of Android.
Now if anyone of you are using 4G on a 3G handset than can you please share the steps?
Thank you.

 

[pr0ph3t]

I heard it possible with some root tricks. However, you can't get 4G speeds.

 

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Can't say his mobile is rooted but he is using 4G in 3G phone. Yes, speed is 3G only.
I wish anyone here knows the tricks?