ACARS Data
@CommanderCYYZ
Others have addressed your question a few times, but to recap: the satellite radio system "pings" the satellites to maintain contact even without sending otherwise useful data. So, by saying in effect "Here I am, are you there?" repeatedly, the system is ready, the satellite is known, etc., for when real data communication is needed.
So the reports that no additional engine data was sent can be true, along with the 4-5 hours of "pings".