Hey @Harpreetbrar! VoLTE really only depends on your carriers as @RobertZ mentioned. We apologize that we cannot help you with problems that can only be solved by your carrier. Thanks!
Your phone supports VoLTE, but you need the INR CSC. Sorry, but Canadian models do not have Indian CSC. Next time, buy a F model (Europe) instead of W (Canada). You can try to flash the G935F firmware but this can void your warranty. For this, visit XDA Forums.
No worries. Really sorry we can't do anything else to help.
(CSC are files in the phone firmware that customizes the phone to behave like the carrier wants(here, Jio). These files include VoLTE functionality, among others. Editing them requires root or updating the firmware. And W models are for Canada, with carriers like Bell, Rogers and Telus. F models have all European carriers, along with other countries like India. These models have Jio's CSC, but not Canada CSC.
So remember: G9xxF or G9xxF/DS models only for Jio features.)
