When you order a telephone from the telephone company, the sales office usually describes - in flowing terms - the most expensive equipment.

Unless you ask, you're rarely told that you could save considerable money by using a standard dial phone. Phone rates vary all over the country, but the savings ratios remain pretty much the same.

In looking at the rates listed by my own phone company in the Washington, D.C., area, I found that the sales department usually touts a "Trimline" pushbotton "Touchtone" model. This combination of slimness and pushbuttons costs $3.55 a month more than the regular desk-model, dial-phone. That's $42.60 a year extra for just renting a telephone. Think about it.

In its January '78 issue, Consumer Reports says phone companies are really pushing the expensive equipment. Naturally, it brings in a lot more money. In some cases, Consumer Reports says, you have to demand an official tariff or rate schedule from the phone company. If you have a hard time finding out about the cheapest equipment, ask to speak to the supervisor.

More and more telephone customers are buying their own telephones and plugging them in themselves. This makes a lot of sense. The phone company just rents its equipment to you year after year. If you buy your own, you can usually pay for it within a year or two on the savings you make from not having to rent. You also save on installation charges.

All this is possible now because the courts told the phone companies they could no longer have a monopoly on equipment supplies. Again, some phone companies may give you a hard time if you purchase your own equipment and plug it in yourself. If there's an argument, ask to speak to the business office supervisor. Insist on your rights.

You can buy telephones from such chain stores as Montgomery Ward and Sears. In some areas there are special equipment stores (listed under "telephone equipment" in the yellow pages).

In general, a standard desk dial-phone costs from $12 to $19 (rebuilt). These phones are sturdy and have a useful life of around 40 years. Usually the savings on rental fees will pay for the phones within one or two years.

You can also get considerable savings on fancier equipment such as push-button dialing and decorator styling. New gadgets like the "automatic dialer" that dials pre-programmed numbers for you, cost a fortune if the phone company supplies them. For example, my phone company wanted to charge a $48 installation fee plus $8.10 a month ($97 a year) for the automatic dialer. A local telephone equipment store sells a similar automatic dialer for $100 with no installation or rental fees. In a little over six months, the thing would pay for itself.

The phone company, according to Federal Communications Commission regulations, must be told when you buy your own equipment. Most companies give you a partial discount on monthly rental fees when you own the equipment. A few give a full discount. The discounts range from 50 cents to $1.50 a month.

Equipment suppliers say some customers refuse to inform the telephone company when they purchase their own extension phones in order to avoid the small monthly charge.

If, however, you are caught using unreported equipment, the company can order you to either remove the equipment or start paying a fee.

Some states claim phone companies don't have the right to collect a rental fee (even a partial one) when you own the equipment. Other states say the phone company does have the right.

Q: Several years ago my husband and I each wrote a will in our own hand. At the time, we were told that handwritten wills were legal. But now we're told handwritten wills might not be legal. What's the status of handwritten wills?

A: According to the latest Martindale and Hubbell Law Digest, handwritten wills are valid in California. But in other states they may not be valid.

And remember, just being "legal" or "valid" is not enough. The will must make sense and be in the proper language to carry out your wishes. Many handwritten wills are not written properly and make for a lot of grief among the heirs. Again, I advise that you get a lawyer to do the job.