ALCS65, they went down 400 miles from Natal (which I'd half expect to be VHF ACARS equipped and 160 miles from Fernando de Noronha (which might be ACARS equipped.) They were pretty much out of VHF communications for quite a period of time. Off hand I cannot find a reference to either of them supporting ACARS. I'd estimate they were a good hour out from any meaningful VHF contact, maybe (much) more. I'd expect the cut over to satellite would happen at or some modest time after the switch from VHF flight control communications to HF.
Released documentation reports the last several position reports as well as the standard ACARS all, they say, through Inmarsat's AOW bird.