1.Install Darklord n5 ROM by darkera13 with default csc.
2.Let it boot and now insert your jio sim. Here VOLTE wont work.
3. Now download these files https://drive.google.com/file/d/0B_z...w?usp=drivesdk
4.Unrar the zip .
5.Now install the root explorer given in the folder.
6.BACKUP the folder "csc" and files CSCversion.txt and SW_configuration.xml and then delete from system .
6.Now copy CSCversion.txt SW_configuration.xml and 'csc' folder to system.
7.NOW select the files csc version and sw configuration, give permissions using 3 dot menu. Enter the octal 0644. and now select csc folder give permission by entering 0755 in the octal code and select Also apply to subfolder option and the 2nd option. Now restart your phone
8.If it stil didnt worked then go to settings and create apn for ur network carrier and save.
9.Now make another apn with name 'ims' and apn 'ims' and save again.
10.It wont show the ims apn but it is still there. Now Reboot again.
11.Congratulations volte will work
HIT THE THANKS BUTTON IF I HELPED. PEACE
THE ROM DARKLORD N5belongs to their respective developer.
for the rom google it with name darklord n5 rc2.1 by darkera13.