Sodium-phosphate symporter which preferentially transports the monovalent form of phosphate with a stoichiometry of two sodium ions per phosphate ion (PubMed:12205090, PubMed:15955065, PubMed:16790504, PubMed:17494632, PubMed:22327515, PubMed:28722801, PubMed:30704756). Plays a critical role in the determination of bone quality and strength by providing phosphate for bone mineralization (By similarity). Required to maintain normal cerebrospinal fluid phosphate levels (By similarity). Mediates phosphate-induced calcification of vascular smooth muscle cells (VCMCs) and can functionally compensate for loss of SLC20A1 in VCMCs (By similarity). {ECO:0000250|UniProtKB:Q80UP8, ECO:0000269|PubMed:12205090, ECO:0000269|PubMed:15955065, ECO:0000269|PubMed:16790504, ECO:0000269|PubMed:17494632, ECO:0000269|PubMed:22327515, ECO:0000269|PubMed:28722801, ECO:0000269|PubMed:30704756}. (Microbial infection) Functions as a retroviral receptor and confers human cells susceptibility to infection to amphotropic murine leukemia virus (A-MuLV), 10A1 murine leukemia virus (10A1 MLV) and some feline leukemia virus subgroup B (FeLV-B) variants. {ECO:0000269|PubMed:11435563, ECO:0000269|PubMed:12205090, ECO:0000269|PubMed:15955065, ECO:0000269|PubMed:8302848}. This is the function of ENSG00000168575 (SLC20A2, solute carrier family 20 member 2).