Sipbroker
http://faq.sipbroker.com/tiki-index....hone%20Numbers
http://www.sipbroker.com/sipbroker/action/pstnNumbers
Unfortunately they don't have pstn access numbers in Italy yet, but you could call one in another country via a cheap calls provider (unlikely with Skype), then enter *01344800079006# - i.e. replace 00 with the Sipbroker prefix *013, then # after the number
this method works for freephone numbers in a range of countries, either via the Sipbroker *013 prefix or some of the other possibilities listed on the page, such as FreeWorldDialup *393*44...
edit - for USA numbers, Sipbroker now uses *1800...