Dorothy and Martin Baier took a convenient detour around the throngs at store sales counters this Christmas. They ordered most of their holiday gifts - almonds from San Francisco, grapefruit from Texas, brass trivets from California's Gump's, and sweaters from a Peruvian import firm - by telephone.
A small stack of unpaid credit-card bills sits as paper proof of the purchases on a corner of Mr. Baier's desk at the Old American Insurance Company, where he is senior vice-president for marketing.
Baier is a direct-marketing expert who has just written the first college text specifically on direct marketing and teaches it part-time at the nearby University of Missouri branch here. From conversations with catalogers, he estimates that about 50 percent of all Christmas sales are made by phone.
In these days of crowded stores and limited service, frequently slow mail delivery, and a general wariness of the costly door-to-door sales approach, the telephone with its speed and sense of urgency is an increasingly popular marketing tool.
Still, there are many who view a phone call from anyone other than a friend as an unwelcome intrusion. And one Chicagoan fairly raced to mail a check to her alma mater after getting a letter that promised no one would phone her (to put the pressure on) if she gave promptly.
''The telephone always interrupts something - there's a negative connotation to it right away,'' Baier concedes. But he admits he is often receptive to telephone sales calls if he has had some prior contact with the seller or if the product is particularly geared to his needs.
He says he is delighted, for instance, when his florist calls to remind him of his wife's birthday, and he gladly accepts a stockbroker friend's advice on what to buy when. He says he would even be amenable to a call from a salesman who might report having noticed the beauty of his yard on a drive by the house and who offers him a product to keep it looking beautiful.
A lot, he says, depends on the approach.
''The pitch man is out,'' he adds. ''The really good direct-marketing effort today is benefit-oriented - it's an attempt to be helpful. . . . And that's the kind of thing that can get your attention, if you happen to be interested.''
If you are not interested or prefer to make your spending decisions in unpressured privacy, Baier suggests saying so. ''Good telephone salespeople are sympathetic and courteous,'' he says. ''If they aren't, they don't get very far.''
More and more telephone sales calls are being made through automatic computer dialing and recorded messages.
Baier says he recently responded favorably to one from Kansas City Mayor Richard Berkley. He was calling on behalf of his wife, Sandy, who was trying to raise funds for the local zoo. But Baier admits he is a good friend of the mayor and contributed to his election campaign.
''I don't think the recorded call has much potential - except maybe for someone like a mayor or . . . some other celebrity,'' he says. And the kind that works best has a live caller both begin and end the conversation, he says.
Calls sometime ago to potential Saturday Review magazine subscribers, for instance, which he says proved very productive, began with a personal inquiry as to whether or not the person phoned had a few minutes to listen to a message from then-Editor Norman Cousins.
But the strongest potential for growth of sales by phone and its most effective use as a marketing tool, in Baier's view, lies in providing the customer with a phone number and letting him take the calling initiative. To trigger that call, often on a toll-free 800 line, the company invites it via television, radio, and newspaper ads or by sending a direct-mail catalog.
Lee Pettit, a spokeswoman for American Telephone & Telegraph Company (AT&T), confirms that the number of 800 lines, on which customers place an order or make a reservation, rose 170 percent between 1977 and 1982. By contrast, WATS (wide-area telephone service) lines, by which many companies contact clients or prospective customers, grew only 71 percent in that period.
This ''call us - we won't call you'' technique has recently spawned a number of telemarketing companies that answer 800 lines for smaller businesses. Order takers can often tell whether a fruit cake or new carpeting is being ordered just by which number is ringing.
Increasingly, Baier says, there is a need for professionals to help in that job. He notes that the telemarketing section of AT&T's Long Lines Division is located in Kansas City, where the University of Missouri recently announced the nation's first graduate program in direct marketing. AT&T has predicted it will hire some 75 people with master's training in direct marketing within the next five years.