I don't think Mode B PoE is still in mainstream use.

These cabins are not large. They did the Ethernet wiring years ago when DSL became available in the area, but there is only a single cable running to each cabin through a PVC conduit so just tearing out the little Leviton plate, putting a new end on the existing cable and plugging it in and then having Wi-Fi, PoE for a phone and a wired plug on their own VLANs is pretty appealing.

They paid something like $60 each and are powering them from a D-Link PoE switch.

They might go "full-stack" on UniFi, but they might also invest in a real hospitality phone system.