There were no pink phones at Gotham’s Union Square Theater for the Aug. 21 preem of “For a Good Time, Call …,” but several attendees knew whom they’d call for a good time anyway.“I would call Barack Obama. I would love to party with him. That would be awesome,” said Justin Long, who co-stars in Focus Features’ femme-centric phone-sex comedy. “Who would I call for that kind of good time? Actually I’d call Ari, she’s a fun girl in every sense of the word,” said Cheyenne Jackson, who’s on Broadway with “Good Time” lead Ari Graynor this fall in “The Performers.” Graynor, who also takes an exec producer credit, said she’d ring writer-producer Katie Anne Naylon, who was inspired by her own phone-sex work in her dorm room at Florida State U. “There were so many funny stories as a phone-sex operator,” Naylon said, “I thought, ‘There’s something to this.’ We use it as a backdrop for two women who become friends, an ‘Odd Couple’ with girls.” Graynor’s roommate and co-star is co-writer Lauren Miller, who was Naylon’s college roomie. “This movie is not a documentary about phone sex but about being as funny as possible. It’s about just having fun,” Miller said. “When we wrote, it we never thought I’d play Lauren, we thought we’d cast some super-famous actress.” As for whom director Jamie Travis would phone? “I text, I don’t call.” Among those at the West Village Ajna Bar afterparty: Seth Rogen, who’s married to Miller, Paul Rudd and a platinum blonde Elisabeth Moss.