HERE’S a moment in the new “Sex and the City” movie, The Post has learned, when Carrie Bradshaw is lounging in a cliff-top Mexican villa, overlooking a breathtaking view of the ocean, with her pink Swarovski-encrusted cellphone in hand. She’s checking her voice mail.

First message.

It’s from Big, who, as many know by now, actually has a name: John James Preston.

“Babe,” he says affectionately, before saying he needs to talk to her urgently.

In a moment of pure impulsiveness, Carrie (Sarah Jessica Parker) throws her phone off the cliff. It goes sailing through the air, with the sun sparkling off the crystals as it falls into the ocean.

It’s ludicrous. It’s exciting. It’s over-the-top.

And it’s achieving what many in the film industry believed impossible just a few years ago: building a cinematic fantasy that’s bigger than Big.

Spoiler alert! Continuing to read this exclusive story will tell you far more about the new movie than has been reported anywhere else. Really. If you want your first viewing of the “Sex and the City” movie to be pristine, we strongly suggest you stop here.

“Everything is bigger,” says an insider familiar with the production. “There’s more extras, there’s more locations and the locations are more fabulous, if that’s possible. And on and on and on.

“The costumes are bigger,” the insider adds. “If an actor is putting on an outfit and [costume designer] Patricia Field says, ‘That outfit needs a million-dollar pin – now it’s perfect.’ That’s happened [on the movie] more than anything on the series. No one shoots inside the New York Public Library. There are a lot of places that no one gets to shoot where we got to shoot.”

Filming locations ranged from the library’s 42nd Street branch and St. Patrick’s Cathedral to more hidden spots – which The Post learned of through the New York Mayor’s Office of Film, Theatre and Broadcasting – including Lenox Hill Hospital, the offices of Vogue and Junior’s in Brooklyn. Last year, the production requested shooting permits for no fewer than 45 separate locations between August and December.

But that’s not all. Everything is gigantic.

There’s the fashion (YSL, Oscar, Ferragamo, Zac, Dior). There’s the branding partnerships (Skyy Vodka, Glacéau Vitaminwater, Mercedes-Benz). There’s the bling (every day the girls wore real jewels estimated at $2.5 million, from deals struck with Tiffany, H. Stern and other top jewelers).

There’s the cameos (Mayor Michael Bloomberg). There’s the sets (a completely rebuilt Fashion Week tent). There’s the hottest new stars (Oscar-winning scene-stealer Jennifer Hudson, playing Louise, Carrie’s adorable personal assistant, who came to the city seeking – what else – love).

And there’s a big plot, The Post hears. Carrie and Big (Chris Noth) get engaged, Samantha (Kim Cattrall) has moved to an LA beach house, Charlotte (Kristin Davis) and Harry (Evan Handler) get pregnant, and Miranda (Cynthia Nixon) and Steve (David Eigenberg) grapple with infidelity.

“If I were to compare the movie to one of the episodes from the series,” the insider says, “it would be the fashion-show episode [called “The Real Me” from Season 4, in 2001]. Just the scale of that episode, in that every single person who walks on camera is famous, and there’s millions of extras and supermodels. It’s a massive episode. So the movie basically starts at that level and goes even further.”

Which is a very good thing.

“I think one of the most interesting scenes that we shot in the movie was at Vogue,” the insider continues. “Which is kind of a big deal because Vogue doesn’t really allow that. There are all these people in it – the photographer at the shoot is Patrick Demarchelier, who is this massive photographer, and Andre Leon Talley is standing there. And all the gowns are, like, $8 billion each one, so that’s a pretty fancy moment in the film.”

Even the heartbreak is bigger than ever.

Sources told The Post that Carrie makes bitterly funny comments about her wedding gown to her trusty threesome. We hear she calls it the perfect thing to be “jilted” in.

She’s all too familiar with romantic devastation. Perhaps, she says, people have seen her in Vogue, where they may be able to touch up “pores” but not “pain.”

Also, we’ve learned that Carrie tells Samantha at one point she’s completely revamping her life, right down to her cellphone area code.

She’s now “347,” she complains.

Samantha tries to comfort her with a reminder that 347 is “the new New York.”

Observes Carrie dejectedly: Bring back the old New York, along with everything else that goes with it. Including her happiness.

As always, the city is practically a character unto itself, a role director/producer/writer Michael Patrick King wanted to be more vibrant than ever.

“We felt this was a really important thing to do,” the insider says. “It’s kind of like a love letter back to New York and America, and an attempt to remind people: ‘Let’s not forget New York is fabulous, and we’re fabulous, and that people love it, and that’s something to celebrate.’

“That’s pretty much why, as difficult as it was to put this deal together for everyone to do the movie, it just became more important that we have fun [with] these people that our country so loves,” the insider adds. “Let’s give it to them. Why are we holding back? Let’s get this out there, let’s have people celebrate this wonderful city and these people that we love and these beautiful locations – all of it.”

Which means exactly what? That salvation comes in an overpriced girly drink?

Yes, if one were to be cheap about it.

But we hear that in one of the more self-reflective scenes, the four friends sit drinking Cosmopolitans. Charlotte remarks on how delicious they are.

Miranda then wonders why they ever stopped drinking them in the first place.

Carrie responds sharply, they had to after the rest of the world started. Early drafts of the script were apparently an “embarrassment of riches,” with the possibility of doing almost 100 pages on any of the minor characters involved, the insider says.

One of the more intriguing new minor characters is Dante, a sexy young LA stud in his 30s who lives next door to Samantha, distracting her from ever-yummy, ever-compassionate Brad Pitt look-alike Smith (Jason Lewis), whose career is now blowing up.

One of the hardest things about living in LA, Samantha tells Carrie, is her hottie neighbor.

She apparently tries to resist this guy, but describes him to Carrie as being the kind of person who is out all the time, switching sex partners at a moment’s notice.

It’s almost as if he’s like someone she knows.

As is clear from the film’s trailer, Charlotte’s pregnancy and Miranda’s marital woes provide key dramatic subplots.

One particularly moving scene occurs, we’ve learned, when Miranda breaks the news of her issues with Steve to his dementia-stricken mother. As fans saw in the series finale in 2004, this relationship was one of the few things that brought out a tender side in the career-driven corporate lawyer.

When she tries to explain the situation, his mother (Anne Meara) apparently asks, “Who’s Steve?”

Carrie then does a classic, irony-drenched “SATC” voice-over, quipping that her friend is starting to see the positive side of Alzheimer’s.

We can only hope the most meaningful – and juiciest – scenes we’ve heard about don’t end up on the cutting room floor.

“We miss these people,” our insider reflects. “It is subversively talking to people about their own lives, and through that they feel things, they reach out to a loved one or have emotions. That’s the whole point.

“Why make people miss them anymore?” the insider continues. “You can’t bring back ‘I Love Lucy’ because they’re all dead. So it just became, ‘Are we going to do this?’ If we’re going to do it, let’s just do it. People want to see it, so let’s do it.”

In one of the early scenes, we hear, Carrie is filled with this exact “let’s just do it” sentiment of certitude in regard to her initial plans to marry Big.

Comparing her past disastrous marital attempts to this one, she tells her friends this time is different.

In that same way, for the generation of fans who have grown in the four years since the series ended, it all feels so different this time.

The giddy boom of the late ’90s is so long gone, it’s hard to remember. But the movie reminds us, with its trademark humor and heartache, what made “Sex and the City” the most iconic – and most quoted – tribute to female friendship of our times.

It’s the love affair with our complicated, completely imperfect city itself.

As Samantha and the girls leave a Fashion Week tent, an activist apparently jumps out of nowhere.

“God,” Samantha wryly says after a beat, “I miss New York.”

Additional reporting by Jennifer Tis and Alisa Wolfson

mstadtmiller@nypost.com