NEW YORK  — Imagine having William Shatner supply your outgoing voicemail message. Or maybe you'd prefer Morgan Freeman coolly telling callers to wait for the beep. Or perhaps havingBetty White joke around is more your speed.

All it takes is $299 and some luck.

The advocacy group Autism Speaks is offering custom-recorded messages from those celebrities as well as Will Ferrell, Carrie Fisher, Tom Hanks, Derek Jeter, Leonard Nimoy, Patrick Stewart and Ed Asner.

From Dec. 3 to Dec. 9, a limited number of 20-second long MP3 messages will be recorded by each celebrity on a first-come, first-served basis for fans to do with as they wish. All requests must be of the PG variety.

Asner, the curmudgeonly Emmy Award winner of "The Mary Tyler Moore Show" and "Lou Grant," dreamed up the unusual fundraiser with his son Matt, who works for Autism Speaks.

"I think people will get a charge out of it," says Asner, who is currently on Broadway in the play "Grace." ''I'll probably say, 'What are you wearing?' Or, 'Take it off.' Something like that."

All proceeds will support autism research and advocacy efforts. An estimated 1 in 88 children in the U.S. is on the autism spectrum, a developmental disorder characterized by communication difficulties, social and behavioral challenges, as well as repetitive behaviors.

If he could get a message from one of the other stars participating, which would Asner want?

"I'm awfully stuck on Will Ferrell, having been subjected to him in 'Elf,'" Asner says. "But they're all such standouts — Patrick Stewart, Leonard Nimoy, Shatner. The list doesn't stop. Even Betty White," he adds about his "MTM" co-star. "She's still got some good left in her."