Get the restaurant's phone number from a guide book.
Dial the number that's in the guide book if you're using a local land line. If you're using your cell phone, you'll have to dial the international access code (011 if you're from the U.S. or Canada, 00 from Europe), followed by Italy's code (39), then the number.
Greet the person who answers the phone by saying "Buon giorno" ("Good morning") or "Buona sera" ("Good afternoon/evening").
Say "Vorrei prenotare un tavola per due" ("I'd like to reserve a table for two") "per strasera/domani sera" ("for this evening/tomorrow evening") "alle venti" ("at 8:00"). Consult your phrase book if you need to tell them a different day or time.
Tell them your name by saying "Mi chiamo _______".
Let them know if you have any special requests. You can do this by saying "Vorremo sederci fuori / vicino alla finestra / con la vista / a una tavola tranquilla" ("We'd like to sit outside / by the window / with a view / at a quiet table").
Tell the host you have a reservation when you arrive at the restaurant by saying "Ho una prenotazione per due persone".