Dihydrosphingosine 1-phosphate phosphatase required for efficient ceramide synthesis from exogenous sphingoid bases (PubMed:10477278, PubMed:10563329, PubMed:10856228, PubMed:11278643, PubMed:11967828, PubMed:12493772, PubMed:12684378, PubMed:12786943, PubMed:9195906, PubMed:9353337, PubMed:9419344, PubMed:25345524). Involved in endocytosis and calcium-mediated signaling (PubMed:10856228, PubMed:11278643). (4R)-hydroxysphinganine 1-phosphate + H2O = (4R)-hydroxysphinganine + phosphate H2O + sphinganine 1-phosphate = phosphate + sphinganine Glycosylated. Belongs to the type 2 lipid phosphate phosphatase family.