You can relay phone calls and text messages through your iPhone to your iPad, so it’s easy to stay in touch no matter what device you’re on.
Use your iPhone to make and receive phone calls or messages on your iPad.
Note: Cellular charges may apply. Wi-Fi Calling isn’t available from all carriers.
Make sure of the following:
Both devices have Get started with FaceTime on iPhone and > FaceTime on your iPhone.
Turn off Allow Calls on Other Devices.
You can send and receive messages—both iMessage and SMS/MMS messages—on your iPad. For more information on iMessage and SMS/MMS messages, see Hand off a FaceTime call from your iPad to your other Apple devices for iPad.
For more information about Wi-Fi calls, see the Apple Support article Make a call with Wi-Fi Calling.