Parlare sul telefono vs parlare al telefono

Question

Given that preposition usage is often idiomatic, are the following expressions equally usual?

• Parlare al telefono
• Parlare sul telefono

Answer 1

Normally Italian people say “parlare al telefono”, the other form is not used at all since it seems wrong.

Conversely, talking about the TV you can say:

L’ho visto alla TV

and also

L’ho visto in TV

quite interchangeably.

Moreover you can also say:

L’ho visto sulla TV Svizzera

but in this case you’re specifying where you watched it.