https://consumerist.com/2017/09/27/delta-now-lets-passengers-send-some-inflight-text-messages/

The next time you’re on a Delta Air Lines flight and want to tell the pal picking you up at the airport that your flight is delayed (or ask your mom to please make sure there are cheese curds in the refrigerator upon your arrival), you’ll be able to send a text message from the air — for free.

Starting Oct. 1, Delta will allow passengers to send mobile messages for free using platforms like iMessage, WhatsApp, and Facebook messenger, by connecting to Delta’s WiFi portal on any Gogo-enabled flight, which includes all planes with two or more cabins.