Is There any way to change the default iphone dialer with jio4gvoice app its annoying if someone calls me it pops up like a notification
If I understand your question correctly, then you want to use the Jio4GVoice app as your default phone dialler?
As far as I'm aware there's no way of doing this and, to be honest, you may not want to as this app isn't playing so nicely with iOS 11 (it doesn't seem to remain in the background properly as it used to under iOS 10).
It may be possible to make another app your default dialler by jailbreaking your iPhone. However, this is not something I would generally recommend anyway.
If you're happy with the app, then the best you can do is probably add it to your dock and hide the default Phone app from view. However, you'll find the default phone app will still be used when tapping on phone links etc.
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