"He put the phone on the table."
Translation:Telefonu masanın üstüne koydu.
üstünde is a state, üstüne is for an action.
"telefon masanın üstünde": is "the phone is on the table"
"masada" is locative, it indicates a static location. You need to use dative (masaya) to indicate action. Telefon masada: the phone is on the table