George Plimpton is a little too monotone, and Kurt Vonnegut rambles a bit, but both are now featured on a service that is fast becoming one of the best ways to promote books.

With BookTalk, readers can dial up their favorite scribes 24 hours a day to hear them discuss their latest works — and publishers are realizing this personal touch is a big hit with readers.

“It really creates a bridge between authors and readers, and that’s (useful) because not everyone can get to a reading,” says Marie Coolman, a spokeswoman for Ballantine Books.

Publishers are now starting to regularly feature BookTalk’s telephone number in their display ads in newspapers and mags around the country — and are seeing direct results.

“We ran a tie-in ad for ‘The Perfect Witness’ with BookTalk in a Chicago paper,” says Coolman, “and the next day they had 400 calls from the Chicago area to listen to (author) Barry Siegel.”

From his Sherman Oaks, Calif., office, BookTalk founder David Knight says that in the last six months, his 5-year-old biz has really taken off, seeing a 25% growth in revenue. New publishing clients include Warner Books; Little, Brown; St. Martin’s Press; and Ballantine.

Authors’ recordings can stay for three months to a year, and publishers pay a fee of $100-$200 per month as rent. Knight’s team has recorded about 1,100 authors.

The service is free of charge, except for the price of the call. The main number is 818-788-9722, but BookTalk currently has local telephone lines in 30 different cities … and counting.

Negotiations are also under way for BookTalk to partner with booksellers, so callers can listen to authors and order books at the same time.

Knight says callers are also fond of leaving messages for the writers, asking questions and sometimes even offering advice on how their phone chat could be spruced up.

In discussing his book “Truman Capote,” Plimpton, according to one listener, should “give us more personality.”

Everybody’s a critic.