For those needing to know the basics of how the ACARS interacts when presented with a VHF or a SATCOM option, the detailed analysis presented in the TSB Canada report into the Swiss Air Flight 111 accident on 2 September 1998, will alert you to method in which ACARS can be routed. Nothing of any importance has changed in this methodology since that date.
A question for the 777 pilots out there. Before all this started, how much did you actually know about the workings of the ACARS? Did you know that it would continue to send pings via the SATCOM, even if it was shut off?