In order to place a call from your iPad, you must have FaceTime setup with an iCloud account that is also on your iPhone.
Please see this Apple Support article to setup your iPad to accept and receive calls that happen on your iPhone.
In order to place a call from your iPad, you must have FaceTime setup with an iCloud account that is also on your iPhone.
Please see this Apple Support article to setup your iPad to accept and receive calls that happen on your iPhone.