Italian Stefano Cabizza couldn't quite find his voice and composure when one day he received that momentous phone call from no less than Pope Francis, pontiff of the 1.2 billion-strong Roman Catholic secular faith.

The minute he heard the other person said "Hello, it's the pope," 19-year-old Stefano remained silent for a few seconds. "I couldn't believe it."

The information technology student from Camin, near Padua in northern Italy, happened to have sent Pope Francis a letter when his family attended a papal mass in Castel Gandolfo on Aug 15. He had entrusted the letter to a senior cleric to give it to the pope.

In the letter, Stefano described his life, shared his hopes and aspirations to the heir of St Peter's throne as well as plans and dreams for the future once he finishes his studies. Much like just how best friends communicate and value their friendship.

Then on Aug 18, his sister Angela told him that she had earlier received a call for him. It was a man but didn't leave his name. Angela said she told the man to call back at 5 pm and that Stefano might already be home by then.

And then the second call happened. This time it was Stefano who answered.

"I am Pope Francis. Let's call each other by our first names."

"He said to me, do you think the Apostles would have used the polite form with Christ? "Would they have called him your excellency? They were friends, just as you and I are now, and with friends I'm accustomed to using 'tu'."

Stefano said Pope Francis wanted him to address the successor of Benedict XVI as 'tu' rather than use the much more formal 'lei' during the conversation.

"We laughed and joked for about eight minutes."

"He asked me to pray for Saint Stephen and for him. He then blessed me and I felt a great strength growing in me."

"It was certainly the best day of my life."