BURBANK, Calif. - Allison Janney extends the maxim that the best actors can entertain simply by reading a phone book. She manages with commercials.

Her voice is warm and burnished with compassion on radio and TV voiceover spots for a health-care provider, possibly the most melodic soft-sell ever.

Then there's her real craft. Consider, for instance, her sharp, take-no-prisoners delivery as C.J. Gregg in "The West Wing," and her manic chatter as a blowsy woman in the indie film "The Way Way Back."

Or enjoy the sly purr she employs as Bonnie, a wayward but good-hearted parent and grandparent who's trying to stay reformed in the new CBS sitcom "Mom" (9:30 PST Monday). Anna Faris co-stars as her similarly imperfect daughter.

"It's acting," Janney said. "I feel like actors like to be challenged and play all different types of roles. For whatever reason, I've been given the opportunity to do so."

That reason, of course, is she is an enormously gifted and appealing performer with a range that's second to none. Her talent has been on display on Broadway, where she earned Tony nominations for "9 to 5" and "A View from the Bridge," and in movies including "American Beauty" and "Drop Dead Gorgeous."

She earned four Emmy Awards for playing White House press secretary C.J. Cregg in "The West Wing."

In person, the willowy Janney is polite and soft-spoken - the product, the Ohio native says, of her proper Midwestern upbringing. She's also prone to a full-throated laugh, along with charming moments of candor and modesty.

Her 6-foot height, she says, earned her some brutal early career assessments from short-sighted agents: One said her roles would be limited to a handful of options, including aliens.

And Janney acknowledges that her 1999-2006 experience on the intricate, densely scripted political drama from Aaron Sorkin ("The Social Network," HBO's "The Newsroom") was something she treasures but also acutely recalls as demanding.

"It was fascinating to be part of that, and all the people in Washington who wanted to be part of it because it's the first time they were made to look good and exciting," she said. Then there was the thrill of "going to D.C. and feeling like a rock star."

The heavy shooting schedule, however, required a commitment that meant missing "a lot of family things, and weddings and funerals," and putting relationships a distant second to work, said Janney, who is single.

A multi-camera comedy like "Mom" offers a different experience, with shorter rehearsal days followed by a Friday taping.

"This is so civilized," she said, both for her and for Faris, "who has a baby and can see her child grow up."

But it's laughs that Janney really is after.

"Comedy is what I love the best. I'm just drawn to it," she said, with Carol Burnett and Mary Tyler Moore among her TV favorites as a youngster. In her early years on stage, in college and with regional theaters, she flexed her comic muscles.

"I just thought it was the most fun you could have," Janney said. Serious drama has its own rewards, she added, but also drawbacks.

"If I have to be in a dark emotional place, I spend my day looking for reasons to be in that state, so I can bring it when I need to (for a role). I can do it, but it's just a lot trickier for me," she said.

With "Mom," Janney sees the best of worlds, a combination of humor with "serious moments of love or disappointment or fear," not just what she calls the "joke-joke-joke-joke" barrage typical of many TV comedies.

She admits to nervousness at work, from the initial script reading to just before the taping begins. It's characteristic, she said, but also stems from working for a TV comedy master, Chuck Lorre, whose hits include "The Big Bang Theory" and "Two and a Half Men."

"It's scary to do a run-through for Chuck. I don't want to mess it up or miss a laugh," she said.

But Lorre, it seems, is putty in her hands.

"Allison is a writer's dream come true. She can literally do anything. And do it brilliantly," the writer-producer wrote in an email. "Physical comedy, sweet poignant moments, heartbreaking scenes, classic straight man, you name it."

Janney is aware that viewers sometimes balk when an actor identified strongly with one character, like C.J., tries on another. But the 54-year-old said she's having a blast as sexy, loose-cannon Bonnie, and CBS ordered a full freshman season of "Mom" on the basis of its initial ratings.

"It's nice to be my age and be sexually active and aggressive - in the parts I play," she said, adding a chortle as perfect punctuation. Of course.

Lynn Elber is a national television columnist for The Associated Press.