Spam calls on iPad

My thoughts are what I wrote.

You don’t get calls on an iPad.

You do get calls on an iPad from an iPhone, via Continuity.

I’d expect Apple would first send notifications to your currently-active devices.

The iPad doesn’t get telephone calls, there’s no voice capabilities, which means you’re getting spam calls on the iPhone via Continuity. Spam texts and phishing and other dreck can arrive the same way too, as the Messages messages are also visible across all devices associated with your Apple ID. Unless Continuity has been disabled. But that also means you won’t get the legitimate messages and legitimate telephone calls across all of your devices.

Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support

When the call is "ringing" on the iPad, it is not ringing on the iPhone; ie., it's just coming into the iPad. Does this fact make a difference in your thoughts on this issue?

That's correct, because you are using iPad at the time the call came to your phone and the iPad is dominant in this scenario. Mr. Hoffman has provided the right answer and you are using Continuity Services, which you can turn off so the iPad will not ring. The iPhone will ring however. On your iPhone, go to Settings > Phone and turn off Calls on other devices.

Unless you also have an iPhone, you cannot receive or make phone calls on an iPad.

FYI: the cellular number is for using cellular data and also for the carrier to bill you.

You're most welcome!