Allow Wifi calling but not ring??

There is no current setting to make calls but not receive them.

 

Go to settings/sound. Turn on " change with buttons ", then turn the volume down. You'll no longer hear the ringer till you turn it back up.

 

Doesn't the mute turn off ringing?

 

Yes, but it also mutes some apps (depending on the developer). For example, I believe if you have mute on, you can't hear sounds in facebook (if i remember correctly). I think youtube will safari will play sounds with mute on.

 

Could you record a silent custom ringtone, sync that to the iPad and use it?

Even easier, just use this one: http://www.howtogeek.com/wp-content/uploads/2016/06/Silent-Ringtone.zip

 

I think changing the ring tone work.