It won't be the only solution that can do this by the way. Many airplane WiFi services block WhatsApp and telegram calls. I think they just look at the traffic

It won't be the only solution that can do this by the way. Many airplane WiFi services block WhatsApp and telegram calls. I think they just look at the traffic shape. Real-time traffic requires a lot of constant similar sized traffic per second, rather than texting or images which is much more bursty.