Is it permissible for spouses to exchange sexually explicit talk over the phone?

A husband should not discuss matters of intercourse with his wife over the phone, because the proper place for such talk is in private. The phone is an insecure medium, as it is easy to eavesdrop and record calls. Some scholars have interpreted "garment" in the verse: (They are a garment for you, and you are a garment for them) to mean concealment. And part of concealment is that the husband should not take a path that exposes what transpires between him and his wife to the knowledge of others.