Is there a way to allow certain phone numbers to ring when you are on airplane mode?

Apart from FaceTime, you can also make --> WiFi Calling --> Make a call with Wi-Fi Calling - Apple Support

Please see the pic below.

if you can't turn on or use Wi-Fi Calling, make sure that your carrier offers Wi-Fi Calling and that your devices have the latest software. Then, follow these steps if you can't turn on Wi-Fi Calling or make a Wi-Fi call. Wait two minutes before you go from one step to the next.

1. Go to Settings > Phone > Wi-Fi Calling and make sure that Wi-Fi Calling is on.
2. Restart your iPhone.
3. Connect to a different Wi-Fi network. Not all Wi-Fi networks work with Wi-Fi Calling.
4. Turn Wi-Fi Calling off and then on again.
5. Go to Settings > General > Transfer or Reset iPhone > Reset, and tap Reset Network Settings.

..WheelieNick..

After making a few searches, delayed replies; I see most what

I'd found had already been posted in this discussion forum.

And so have erased those duplicate ideas; except to say this

topic has been mentioned to some depth in ASC Lounge.

• Use Airplane Mode on your iPhone, iPad, iPod touch, and Apple Watch - Apple Support

//support.apple.com/en-us/HT204234

"If the airline allows it, you can use Wi-Fi and Bluetooth while

in Airplane Mode. ~You just need to turn them on separately."

"Airplane Mode may also turn off Wi-Fi and Bluetooth (in Control

Center) unless you turned them on, while in Airplane Mode."

.So as to not advocate a Second set of Circumstances ~Yours is 'Apple' correct.

Yes, as WheelieNick said, you cannot make voice calls when on Airplane mode. However...

When on Airplane mode you can make FaceTime Calls through WiFi.

Please see the pic below.

no, when on airplane mode, you cannot make or receive calls