Real estate investors and brokers around the country will be able to plug into a sophisticated, computer-based problem-solving network early this fall to sell, exchange or buy anything from condominium units to waterfront development property--often with no cash involved.

They'll be able to take their portable real-estate terminals with them wherever they go, send and receive electronic mail, custom-order mortgage financing, arrange for accounting and legal advice electronically, and trade mortgage notes for manufactured goods in the $40 billion corporate barter market simply by hitting the right buttons.

That, at any rate, is how Charles Huggins says the new national Exchange Network will work once it gets rolling in September.

Huggins, 52, a wealthy real estate entrepreneur from Maryland, is bankrolling the network from an office in Palm Beach Gardens, Fla. His firm's commercial service will go on line Aug. 1, using the 56-city telecommunications network of CompuServe Inc. of Columbus, Ohio.

Once it has its first 1,000 members--which Huggins expects to sign up before October--the system should have enough property and information features to function as a true national electronic investors' exchange.

The initial clients will be, like Huggins himself, professional real-estate exchangers affiliated with the 300 local exchange groups around the United States. An estimated 15,000 exchangers currently are active, with the largest memberships in the Sun Belt, Middle Atlantic and West Coast states.

Exchangers emphasize solving the "people problems" of real-estate ownership and investment, and look for alternatives to traditional cash sales. They use federal tax-saving techniques such as Section 1031 tax-deferred swaps wherever possible, and depend heavily on their contacts with fellow exchangers to market properties.

For example, let's say a small-scale investor in Boston needed to dispose of a rental house because he no longer could afford its negative monthly cash flow. An exchanger might link him up with a California woman who'd like to sell a portfolio of first and second mortgage notes, yielding 18 percent a year.

The Boston rental-home investor would walk away with income-producing notes rather than a cash price for his real-estate equity, in other words. The California woman, working through a West Coast exchanger, might never take title to the far-away East Coast rental property. Instead, she might end up with $50,000 worth of antique cars, swapped by a Chicago collector willing to buy the Boston house at a discounted price for his daughter, a newly married graduate student at MIT.

Problem-solving exchange transactions like these, sometimes involving 10 to 12 individual buyers and sellers who never meet, can be highly complex.

The pressing need for a reliable, national, electronic link among exchangers, individual investors and traditional real estate brokers "is what gave birth to the network idea," Huggins said. "Nothing like it exists anywhere."

Although the National Association of Realtors has a computer-based system called REINET, it functions primarily as a national multiple-listing service for commercial and industrial property, land and high-priced homes.

Huggins said that his network is designed to be "complementary" to REINET, "but very, very different."

The services available through the Exchange Network, for instance, will range from real estate and barter listings to "information-base access" via electronic newsletters on real estate, taxation and financing.

Network's property listings will include the sort of "people" data that exchangers require: details about why the seller of a piece of real estate wants to sell; details of the likely range of goods or services the seller will accept, in addition to cash price, and information on the exchange broker handling the listing. Along with these will be the usual data on existing financing, property characteristics, property taxes and income.

Huggins said that network users will be able to shop for mortgage money electronically via connections with major mortgage brokers. (They'll be able to send loan applications via electronic mail to the plugged-in lender they select.)

The network also will maintain electronic "bulletin boards" of meeting and conference notices, and goods for barter ("such as gems, computers, whatever people want to throw into a deal"). It also will connect investors with what Huggins insists "will be the top professional advisers in real estate"--from tax lawyers to barter experts--to handle transactions in any state.

Membership in the network won't be inexpensive. Everyone joining will have to buy and use the same portable computer equipment and software, receive two to three days worth of training before going on line, and pay a membership fee of $200 a year. Individual property listings on the national network will cost $25 apiece. The total initial package, with computer, training and software, will run $5,960.

For information on the electronic real-estate exchange, write Exchange Network Inc., Suite 208, 4360 N. Lake Blvd., Palm Beach Gardens, Fla. 33410.