Apple iPad mini (6th generation) cannot make calls or send messages

The checks in more detail

Apple's page for calls that fail lists Airplane Mode, Do Not Disturb, blocked numbers and carrier settings. For messages, Settings, Messages, make sure iMessage is on and Send and Receive shows your number and email; a missing number stops messages arriving. If the iPad is cellular, check that the plan supports SMS. A restart and an iPadOS update fix many sync problems. A mini that rings but cannot be heard needs the microphone check. Sign out and back in to iMessage if messages stop.

If you rely on the mini for FaceTime, check that it has a front camera free of dust and that the microphone on the top edge is not covered by a case or your hand, since the mini is small and easy to hold over the microphone. Test with a call to a friend and ask whether they hear you clearly, and check Settings, FaceTime for the addresses the iPad can be reached at. Note that cellular mini models can use an eSIM for data but not for ordinary phone calls on their own plan in most countries,

so the number on the mini is for data and the iPhone relay handles calls. Check the cellular plan details with your carrier so you are not surprised. If you use a Wi-Fi iPad mini, remember that it has no phone number of its own, so messages to your number appear only if the iPhone forwards them with Text Message Forwarding turned on for the iPad, in the iPhone's Settings, Messages, Text Message Forwarding. Turn it on for the iPad, enter the code shown, and SMS messages arrive on the mini as well as iMessages.