Like it or not, your relationship with your home telephone is about to change. The government broke up American Telephone & Telegraph's telephone monopoly last year and the effects are finally starting to come home. You may eventually be paying for telephone service in a different way. And instead of renting your phone from Ma Bell, as most people do now, you'll probably want to buy it outright. Here are the answers to some of your questions about the telephone revolution:

* I thought I already owned my telephone? You own it only if you went to a phone store, bought it and had it installed. You are renting it if you ordered the instrument directly from the phone company, which installed it at no extra charge. A rental fee of a few dollars is added to your phone bill every month.

* May I continue to rent my phone? Yes, for the present. It is generally more expensive to rent a telephone than to own it. But it's also more convenient, as long as the phone company will come to your house and make repairs. When you own a phone, you have to get it to a phone center for repairs, or pay for an in-home visit.

Three separate entities are coming into your life: (1) Your local phone company which, next January, will be folded into one of seven, new regional companies regulated by state governments; (2) AT&T, running regulated long-distance service and manufacturing deregulated telephones and other equipment; (3) American Bell, born this month as a fully owned subsidiary of AT&T, responsible for selling telephones and future services (like automatic message-taking if you're not home when the phone rings).

Starting next January, responsibility for rented telephones will be transferred to AT&T. You will still be paying the rental bill through your local phone company, so nothing will change at first. Eventually, however, you may get two separate bills: one from your phone company for local calls and such services as push-button dialing, and one from AT&T for phone rental and long-distance service. You might also be able to buy long-distance service from another company. In 1984, or later, telephone-rental charges will also be deregulated.

Starting next year, rented phones that break will be repaired by AT&T, not by your local phone company. A serviceman may come to your home, or you may want to take (or mail) the phone to a service center.

* What about independent phone companies that aren't part of the Bell System? Each will be setting its own policies, but the trend is toward selling phones rather than leasing them.

* Can I buy the phone that is now in my home? Yes. Several phone companies have them for sale right now; all the Bell companies are expected to be selling them by spring. If your instrument is old, consider having it reconditioned or replaced before buying. Local phone companies will be selling phones this year as long as their supply lasts. Next year, all sales of AT&T equipment will be transferred to AT&T or American Bell.

* Do I have to buy an AT&T phone? No indeed. AT&T instruments, made by Western Electric, have a fine reputation for reliability. But phones are also made by other reputable companies like International Telephone & Telegraph and General Telephone & Electronics. Many styles are available, at many different prices, at department stores and consumer-electronics stores.

When buying a phone, consider the convenience of repair. Is there a convenient service center for this particular make? Or will you have to mail it to a repair center? The fancy new electronic phones require more repairs than standard phones. But standard phones may become so inexpensive that when they break, you'll throw them out and buy a new one.

* Will new customers still be able to choose between renting and buying? Yes. The phone company or AT&T will continue renting phones for the foreseeable future.

* How much will I save by buying instead of renting? Compare the purchase price of the telephone with the money you would save by having the monthly rental charge removed from your phone bill. Standard phones will probably pay for themselves in a year or less.

* How can I change telephones, if my present phone is permanently attached to a box on the wall? Nothing is permanent. Phone stores sell inexpensive kits for converting your wall box to a jack and attaching a plug to your phone wire (or the phone company will do it, for a price). New houses are built with jacks, and new telephones come with plug-in wires.

* What about phones for home businesses? At present, the local phone companies are selling only single-line phones (without hold buttons), which exempts most business phones from the sales program. But you can buy business phones from American Bell and other companies.