And you thought those calls asking residents to switch from AT&T to Sprint were annoying.

How about having a sniper ring you at a public phone booth and explain that he’ll pull the trigger if you hang up?

That’s what happens to Stu Shepard (Colin Farrell), a hotshot celebrity publicist who’s made a career from “the sin of spin.” As part of his daily stroll down the streets of Manhattan, Stu stops by a phone booth at 53rd and Eighth Ave. He takes off his wedding ring, calls a fresh-faced ingenue he is representing (Katie Holmes) and tries to talk her into a rendezvous.

But when Stu next picks up the phone, it is a sniper’s voice he hears. The Caller (Kiefer Sutherland) begins playing mind games with the stranded publicist. Before long, Stu is having a dog day afternoon, trapped in a phone booth surrounded by police and media who believe HE’S the gunman.

It’s always entertaining to watch a film that is an experiment in environment. As soon as its central conflict is put in motion, “Phone Booth” plays out as a tidy little thriller.

With more than 50 filmed scripts to his credit, veteran screenwriter Larry Cohen has learned that economy of ideas is crucial. Cohen’s latest is so austerely focused that it could operate as a stage play. (In fact, it’s based on a 1996 NYU student film called “End of the Line.”) This is a script where dialogue is everything.

The bantering between Stu and The Caller is quite clever, as both men jockey for position within an ever-changing situation. Cohen’s best gambit is how he sets up the reason why the police (led by Forest Whitaker) are legally unable to listen in on the conversation.

Only sporadically does this streamlined effort get bogged down with extraneous plots (why make Whitaker’s fellow negotiator antagonistic of him?) and lame characters (an Eminem knockoff who is a client of Stu’s).

Colin Farrell stars as a man pinned down by a sniper who won't let him hang up in the thriller Phone

However, uber-commerical filmmaker Joel Schumacher (“Bad Company”) does everything in his power to try and clutter the simple storyline with visual bells and whistles. Schumacher seems so enamored with the cinematic options available in the digital age that he tries to force-feed them all into one movie.

The picture’s intro is emblematic of the director’s latest fetish. It features a special effects sequence that opens on a communications satellite then plummets straight down to the Earth, growing smaller until it’s observing the micro-workings of cellular technology.

Joel, this ain’t “The Core.” It’s a thriller.

He follows this up with every modern means of enhancing images: bullet time, extreme fast motion into slow motion, exaggerated close-ups. Over this booms a narration about phone usage in New York. You begin to think you’re watching a slick commercial for Verizon until the profanities start bombarding the screen.

Fortunately, all the clatter doesn’t spoil the easy-to-get-wrapped-up-in plot.

Irish bad boy Farrell seems comfortable in the lead role, even when tackling a Bronx accent. More importantly, he easily glides from smarmy to sympathetic. His fast-talking character could have been cartoonish — you don’t want to see Superman in that booth — if Farrell hadn’t found a way to bring the man’s innate vulnerability to the surface.

The audience may not like Stu, but they can always relate to him. They certainly are never on the side of the killer, even if he does get most of the good lines. (When taunting Stu with the prospect of firing on his actress friend, The Caller says, “I think she can use a new head shot.”)

As with most Hollywood offerings, the movie’s ending lacks the dramatic knock-out the audience craves after investing in such a harrowing scenario. It’s like an unfinished cellular phone conversation that slowly drifts into static: unsatisfying but too commonplace to get upset about.