Yes, the StreamLine Unit does deliver power over 2-wires. The Dongle adapter translates power from the 2-wires over to the RJ45 phone side. The Dongle can be located up to a distance of 1200ft (365m) from the StreamLine Unit. The phone is not locally powered. eg. not from a power brick.
For a brief description, including FAQ, please refer to the corresponding product bulletin, PA20120267