Part of the ABC transporter complex PhnCDE involved in phosphate import. Responsible for energy coupling to the transport system. ATP + H2O + phosphate(out) = ADP + H(+) + 2 phosphate(in) The complex is composed of two ATP-binding proteins (PhnC), two transmembrane proteins (PhnE) and a solute-binding protein (PhnD). By phosphate-limited conditions, via derepression by PhnF, and probably also via the two-component regulatory system senX3/regX3. Belongs to the ABC transporter superfamily. Phosphonate/phosphate importer (TC 3.A.1.9.2) family.