The official story is the sat was receiving MAL craft pings but the airline didn’t subscribe to the service.
Someone also mentioned a few days ago that engaging the landing gear sends a ping.. and no such ping was ever received.
ACARS can be sent both via VHF radio and satellite - but Malaysia Airlines had not subscribed to the satellite version from London based provider Inmarsat.
Nevertheless, a satellite transmitter on the plane was pinging an Inmarsat satellite with empty data packets. And it is those that have allowed the plane’s position to be estimated on two tracks either side of the satellite.