Enables sodium:phosphate symporter activity. Acts upstream of or within phosphate ion transport. Located in apical plasma membrane. Is expressed in several structures, including digestive system; endoderm; optic vesicle; otic placode; and otic vesicle. Human ortholog(s) of this gene implicated in pulmonary alveolar microlithiasis. Orthologous to human SLC34A2 (solute carrier family 34 member 2).