Catalyzes, at least in vitro, the hydrolysis of sphingomyelin to form ceramide and phosphocholine . Also hydrolyzes 1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine (lyso-platelet-activating factor) in vivo . Also acts on 1-acyl-2-lyso-sn-glycero-3-phosphocholine (lyso-PC) and sphingosylphosphocholine (, ).
Subcellular locations: Cell membrane