"I speak on the phone with my daughter."
Translation:Parlo al telefono con mia figlia.
Mia is my, figlia is daughter. You need to have "mia" go first to place ownership - MY daugher not daughter my.
Also as Ferdinando mentioned above, sul would be "on top of the phone" vs the intended "through the phone" which is an idiomatic - the italian idiom to use is "a" + "L" (article for telefono) = al