I wouldn't have thought it would be that hard for the Motion Picture Association of America to arrange with phone companies to set aside (for a reasonable fee) ten or twelve completely different numbers that would never be assigned to subscribers, so that when a character in a movie/TV show used a phone number, one of those numbers would be chosen, and so sound convincing. (The movie producers could pay a license fee for each number they use in a movie, so financing the operation.) Of course, the same numbers would need to be set aside in every area code so that no phone subscriber's number would be used, but that doesn't seem to me to be a big obstacle.
Yes, the same numbers would be used over and over, but the chance of a realistic number being remembered from one movie to another is slight. That's why I'm suggesting a dozen or so numbers be available to choose from - it would lessen the chance that phone numbers would be recognized from one movie to another.
Ah - if only they asked me....
A reader writes:
As to your 555 rant, I have had some personal experience along those lines. You may remember that in The Conversation, much was made of Gene Hackman's character's attempt to track down a specific phone number. Toward the end of the film, he finds it, and it is briefly shown on screen. It was not a 555 number. Around the time the film came out, I was working for KGO.It was shortly after the Patty Hearst kidnapping, and I was working on that pretty much every day for ABC News. KGO News was a smaller operation then and had only three extension for the news department. This sometimes became a problem for the network people trying to call New York. They decided to have a private line installed in my editing room. Guess which number we got. Often at our busiest moments that phone would ring, and it would be someone who had just seen the film. Their most common reaction was, "ABC News? Far out!"