When Inspector Pazzi uses the pay phone to call the posted phone number about the reward for Dr. Lecter, he inserts coins into the slot on the phone. Because of the low value of the Lyra, Italians use stored-value phone cards for making phone calls.
Okay, think about this. How many average Americans watching this movie are going to know this about Italian phones? It's a lot easier for the creators to just make it a pay phone and have all the average Joes out there know what he's doing when making the call; instead of the confusion it might produce with him using a card to make it.
Actually that's not true at all... In Italy (where we live) there are public telephones working with coins, as well as with phone cards... the real mistake of this scene with Inspector Pazzi is another one: there's no way to call back a public phone in Italy, as it doesn't have any phone number associated with it. You can just make phone calls with them, not receive them... bye ! Marco & Julia