Chairman Sherry Lansing has been there. So have Mel Brooks, Cyd Charisse, Billy Crystal, Sandra Dee, Jodie Foster, Art Garfunkel, Tommy Hilfiger, Mary Tyler Moore and Carl Reiner. That's not to mention Ron Howard, Henry Mancini, Wolfgang Puck, Bonnie Raitt, Ben Stiller, Wendy Wasserstein and Pia Zadora.

They have all been unidentified, unseen "callers" to Dr. Frasier Crane's radio show on "Frasier." As the series moved from neophyte to heavyweight to legend, doing "Frasier" became the hip thing in Hollywood.

But it didn't quite start out that way, casting director Jeff Greenberg says. "I had to call in a few favors for the pilot," he recalls. "I got Griffin Dunne and Linda Hamilton, both of whom happen to be friends of mine. That whole first season I called in a lot of favors. We used John Glover, Amanda Donahoe, Jeff Daniels, Eric Stoltz and a lot of good people. But the intention was never to stunt-cast. It was always just about getting the best actor."

However, there was a method to Greenberg's madness. His goal was to get performers one wouldn't necessarily see on a half-hour sitcom, while at the same time casting a voice that fits whatever problem the character happened to be calling about.

"So, we've wound up with people like Helen Mirren, Stanley Tucci, John Turturro, John Waters, Katarina Witt, Dominick Dunne, Isaac Mizrahi and even Yo-Yo Ma," Greenberg says. "It's fun to get people who aren't really actors, like Bobby Short and Scott Hamilton."

No actual celebrities were harmed -- or even mentioned, except in the end credits -- during the filming of the segments. "We worked hard to make sure we got people whose voices weren't particularly recognizable, since it would take them out of the character they were supposed to be playing," Greenberg notes.

Greenberg says he was able to get increasingly bigger names for the show as it went along. And it was exceptionally easy to cast for the simple reason that the voice-over could be recorded over the phone.

"We patched them in to our recording facility from wherever they were and inconvenienced them for all of 10 minutes," he says. "We'd call them at home, fax them the script and they'd sit on the phone with one of our producers reading lines. And because they're supposed to be on the phone anyway, it sounded fine."

Of course, other guest stars on "Frasier" actually appeared on-camera. That impressive list includes semiregular Bebe Neuwirth, Elvis Costello, Marg Helgenberger, Bob Hoskins, Michael Keaton, Robert Loggia, Brittany Murphy, Tony Shalhoub, Patrick Stewart, Jeanne Tripplehorn, Sela Ward and JoBeth Williams.

"We've had a lot of big actors work in their first sitcom on 'Frasier,'" Greenberg notes. "People like James Earl Jones, Sir Derek Jacobi, Mercedes Ruehl and Laura Linney."

Greenberg is also the guy who put together the phenomenal "Frasier" lead cast. Unlike its more transitional predecessor, "Cheers," the primary players remained essentially unchanged throughout the show's run.

"This cast came together like magic," Greenberg says. "There was a clamor among actors to be in the show. But it was still a long shot, a spinoff of an iconic show. No one predicted it was going to be a hit. But from the first table read on, you could see that every peg was fitting into every hole perfectly. Everyone was blown away by that."

The fact that the audience already had nine years of familiarity with Frasier Crane helped the show's prospects immeasurably. But the other casting was fortuitous. For example, David Hyde Pierce never even read for the part of Niles. It was simply a matter of casting associate Sheila Guthrie remembering Pierce's picture and how much he bore a resemblance to Kelsey Grammer.

"Both sides took a leap of faith," Greenberg recalls. "He was hired without reading, and David said yes without seeing a script. There had never even been a plan to have a brother character until David came along."

Then there is the story of how Peri Gilpin was cast as Roz. The part was originally offered to Lisa Kudrow. By the middle of the following week, the producers had changed their minds and switched their support to the other finalist, Gilpin.

"It was painful for us because we loved Lisa both personally and professionally, and she was doing what she was hired to do," Greenberg recalls. "But it became clear that she wasn't the right fit. Lisa was devastated. But things worked out OK for her on 'Friends,' didn't they?"