Let’s start on your iPhone. Go to Settings > Phone > Calls on Other Devices. Here you’ll see a list of other devices signed into your Apple ID.
To enable this feature completely, you’ll have to also enable it on your other devices. For the iPad, go to Settings > FaceTime > Calls from iPhone. Make sure this is green-checked. Now your calls will ring on your iPad if your iPhone is nearby. But you can go a step further and allow your calls to forward to your iPad even when your iPhone is not nearby. Select Enable Wi-Fi Calling to allow this feature.
Check Calls from iPhone, and if you want, you can also enable Wi-Fi Calling by clicking the button below.
For SMS texts, all you have to do is go to Settings > Messages > Text Message Forwarding. Here you’ll see your other devices signed into iCloud. Check the ones you want to enable, and now you’ll see texts on your iPad and Mac as well as your iPhone. You can even send an SMS text from these devices!
That’s it! You’re all set to answer phone calls and texts on your other devices.