ITU, satcom and ACARS
ITU is a UN body funded by countries hosting the major players in their sphere of influence, with lobbying by those players aimed at preserving their monopolies or at least dominant positions within their respective industries. In this case, I suspect the satcom carriers and perhaps a/c nav equipment providers would be the major forces. Follow the money.
Satcom LINK management, as outlined very early in this very large body of comments, uses "pings" to set up and maintain said link between the a/c and ground. A link to an a/c may be used to carry communications under subscription agreements between that a/c's operators and the satcom provider.
The takeaway summary: satcom link messages exist without ACARS data messages, the latter being subject to subscription payments. Please don't conflate the two.