I phone 7 -Sim Not Valid !!! I shifted from Canada to India..Previous subscription with

That means the phone is locked to a carrier. Likely the one which was used on the phone in Canada. The only way to get the phone unlocked is to ask the carrier the phone is locked to to unlock the phone. Apple can't unlock the phone. We can't help you unlock the phone. The carrier needs to unlock the phone.

See this link --> How to unlock your iPhone for use with a different carrier - Apple Support