Don't laugh -- it beats a dial tone!

''Hello. This is a French chef answering Steve's telephone,'' says the voice in unmistakable rounded tones. ''Steve's not home right now, and I'm in the middle of separating my eggs - it's all part of Steve's buffet for 19. So please wait for the tone - or as they say in France, Attendez pour le beep - and leave your name, a brief message, and your call will be returned. Bon appetit.''

Tom Yanok and Mary O'Connor have a hang-up about taped phone messages. They think they're too dull. Blending their musical and writing skills, they've set out to liven up boring answering machine tapes with some custom-made fun.

The idea first rang a bell with them in early 1981 while they were working on jingles and other novelty pieces at a rented recording studio. Someone persuaded them to record a musical tape for an answering machine. Soon others wanted tapes. The word-of-mouth business grew until they could hear cash register bells ringing.

Today Tom and Mary spend about 15 hours a week in the studio recording 29 -second masterpieces like ''The Evangelist'' (''Believe, brothers and sisters, that your call will be answered'') and ''The Good Witch'' (''Now click your heels together three times and say, 'There's no sound like the tone, there's no sound like the tone . . .' ''). Their library of tapes has grown to about 50 characters and jingles, designed for both personal and business use.

Mr. Yanok and Ms. O'Connor took quite different routes to becoming the Rodgers and Hart of the telephone. She studied fine arts in Boston and then headed for Europe in a flamenco dance troupe. Returning to the city, she founded Telebelles, which delivers singing telegrams (by phone or in person). Later she expanded the coterie of messengers with belly dancers and classical quartets.

He majored in voice and composition at Temple University, once sang with the Philadelphia Orchestra, and now teaches voice. Having started as a Telebelles messenger, today he's a partner in the company.

The team keeps overhead low by doing nearly all of the writing and performing themselves.

''Mary writes a lot of the copy because she's so good at it,'' says Tom. He does most of the singing and uses a synthesizer to imitate almost any instruments needed, including drums. If extra voice parts are called for, he records them one by one, then dubs it all together to become his own trio or quartet.

All the tapes are copyrighted, and the team doesn't expect pirating to be a problem.

''It took us about six weeks just to master how to mix the sound so that it you get a clear recording over the phone,'' Tom says. ''It's hard to rerecord on a home stereo. That's why we stress that our tapes are studio-recorded.''

Before turning the hobby into a business, the team did a little market research.

''We found that about 3.5 million people have answering machines,'' Tom says. ''If we can sell to just 100,000 of them in the next five years, we'll be rich.''

With prices starting at $20, the operation is just breaking even so far.

''People should remember that the special closed-loop tapes cost $7 when they're blank,'' Tom says.

''Only one other company that we know of (in California) is doing this. They're doing mostly impersonations. We'll do them, but it might mean bringing someone to the studio for the voice. That adds to the cost, which we're trying to keep down. We'd rather do something original - custom-tailored for the person.''

Although still excited about turning close encounters with taped messages into half-minutes of comic relief, the team's goals are even loftier.

''We can do a lot of things,'' Yanok says. ''We've created musical revues for shopping malls and civic and business groups. We've made a record and we'd like to do more. For example, Amway came out with an album of songs that its employees could cheer to. We'd like to do things like that.''

In the meantime, new works like ''Soap Opera phone'' and ''Samurai phone'' are on the way.

''Now that we've been doing it a while,'' he says, ''we're starting to come up with some really crazy ideas.''