Sadly, this charming scene from the book, Harry Potter and the Prisoner of Azkaban, never made it into the film.
"Ron Weasley, who was one of Harry's best friends at Hogwarts, came from a whole family of wizards. This meant that he knew a lot of things Harry didn't, but had never used a telephone before. Most unluckily, it had been Uncle Vernon who had answered the call.
'Vernon Dursley speaking.'
Harry, who happened to be in the room at the time, froze as he heard Ron's voice answer.
'HELLO? HELLO? CAN YOU HEAR ME? I — WANT — TO — TALK — TO — HARRY — POTTER!'"
Via Warner Bros.