Easy Peasy!! And very helpful for those times when you hear your iPhone ringing, and your phone is someplace else.   As long as your iPad & iPhone are both running iOS 8, and are on the same Wi-fi connection, making and receiving calls on your iPad is a breeze.

Incoming calls show the caller name, their phone number and their profile picture–assuming there i a profile picture in your contacts.  Just click or swipe on the notification to answer the call.  And the best part is that you can even respond with a quick text message if it is inconvenient to take the call.  

To make a call on your iPad, just tap on a phone number from your contacts list or any phone number displayed in Safari.

To set-up your iPad so that you can make and receive calls go to Settings 

FaceTime and select iPhone Cellular calls to the “on” position.  

You can also choose to receive FaceTime calls. And choose which of your connected phone numbers and email addresses will share your cellular connection between your iPad to your iPhone when on the same Wi-fi connection. In other words, you can be selective.