In coming years, phones are expected to be more computerized, displaying the number being called and monitoring burglar and fire alarms.

With ownership will come responsibility: Consumers will have to be concerned with the quality of various telephones and how to get them repaired - now handled by the phone company. People are already finding, according to some retailers, that some phones are not as reliable as those offered by the telephone company.

''Telephones are not going to last 25 years anymore,'' said Anthony Lockhart, editor of the Residential Telephone Systems Monitor, a newsletter and survey covering the residential phone market. ''But I think people will come to accept that. They'll just treat it like any other consumer product.'' Maintenance Questions

In the event of a breakdown, the consumer will have to determine whether the trouble is in the line or in the phone. If in the line, the local telephone company has the responsibility for repairs. If in the phone, the consumer must get it fixed. PICK UP 1ST AND LAST ADD PHONES

In this new era, consumers will plug their own phone into the wall and pay only for the calls they make. Such a change, however, might be hard for some consumers, long accustomed to leasing their phones. Some state regulators are concerned that arranging for maintenance will be particularly difficult for some people.

''A large percentage of people prefer to lease, and moreover they prefer to lease primarily because it guarantees that maintenance is available,'' said Eric J. Schneidewind, chairman of the Michigan Public Service Commission. ''I and my colleagues are worried about a large number of customers who may not be able to get someone to install or to come out and maintain equipment of a basic variety,'' he said.

Mr. Schneidewind said the problem would be most severe in older, poorer neighborhoods, where buildings are not equipped with modular jacks. Mr. Schneidewind and some other state regulators want the states to have the power to require local phone companies to continue to install and maintain phones for those who cannot do it themselves.