It must be great sport to poke fun at Ma Bell. In one TV ad, a not-so-debonair dude is telephoning his girlfriend, who lives on the other side of the country. To save money, he calls her after 11 p.m., his time. Unfortunately, she had gone to sleep several hours ago. So she hangs up on him.
The purpose of this and other clever ads is to show how much cheaper it is to make long-distance telephone calls with a privately owned long-distance service than it is to use American Telephone & Telegraph (AT&T) facilities.
These private services, which include MCI Communications, Western Union, ITT's Longer Distance, Sprint, and the SBS Skyline, all like to compare their costs with AT&T's. They don't like to compare their costs - or services - among one another. But people thinking of subscribing to one of these services should do this comparison.
In some parts of the country an extensive comparison is not yet possible, since only one or two of these alternative services - known as specialized common carriers (SCCs) - are yet available. These companies started their rapid growth by concentrating their efforts on routes where long-distance traffic was heaviest. Now, however, the list of cities with as many as five SCCs is growing rapidly, creating a maze of service fees, monthly charges, billing increments, and different costs for different times of the day.
Some help in getting through this maze is provided by a recently published paperback book: ''Reverse the Charges; How to Save Money on Your Telephone Bill, '' by Samuel A. Simon and Joseph W. Waz Jr. (Pantheon Books, $2.95). Mr. Simon is executive director of the Telecommunications Research and Action Center, a nonprofit consumer advocacy group in Washington, D.C.
''It's going to take some time and effort to find out which service is better for each consumer,'' Mr. Simon said in an interview. But making that effort can save you 25 to 50 percent on your long-distance calling, depending on where you call and the time of day you do the calling.
The first step in choosing an SCC is to look at where most of your long-distance calls go. Then find out which companies reach those areas. This consideration will become less important, however, as the year goes on, since most companies will reach the entire country by the end of 1983.
The next step is to figure out when you make the most long-distance calls. As with AT&T, most SCC rates are lower in the evenings, and even less expensive late at night and on weekends. But even at these times the differences can be quite wide. If most of your calls are made on the weekend or late at night, you might prefer ITT's Nightline or MCI's Weekender services.
If most of your calls must be made during daytime hours, however, the SBS Skyline service will save more money.
Although the ads for these services say they're best for people who have $25 or more in long-distance charges each month, with services like Nightline or Weekender it may pay to subscribe even if you aren't that long-winded.
With some services, including Sprint, ITT, MCI, and Western Union, a call can originate from any phone; the call is billed to your account by dialing any Touch-Tone phone. This saves the trouble of ''calling card'' or credit card calls, operator-assisted calls, or collect calls.
This also allows you to give the authorization code to relatives or co-workers and have the bills sent to you, along with a complete record of where the calls originated and the numbers called.
With some companies there is a minimum monthly service fee, like $5 or $10; with others there's a minimum monthly bill, perhaps $10 to $15. You'll have to compare recent bills from Ma Bell to see if expected savings will offset these fees and minimum charges.
In most parts of the country you have to dial a long number of digits to complete a long-distance call on one of these private services. For a while, at least, 22 to 24 numbers will be the norm, compared with the 11 you are used to. But in a few places, SCCs have won the right to offer ''single-digit access.'' So just as you dial ''1'' for a regular long-distance call now, you only have to dial ''6'' to make a call with MCI, or ''8'' for Sprint.
In the not-so-distant future, thanks in part to the AT&T divestiture plan, one requirement that all SCCs now have - the Touch-Tone phone - may be eliminated. With single-digit access, you can make an SCC-relayed call without having to rely on a push-button phone or a special touch pad converter for your dial phone. Until that day, though, you're better off having a Touch-Tone phone if you plan to make a lot of SCC-assisted calls.
Also thanks to the divestiture, customers in the future will be able to select from any number of long-distance services, including MCI, Sprint, and Western Union, as well as AT&T - which is expected to become more competitive on its long-distance rates.
Whether or not you do this homework now, it's likely you will have to do it in the future, and you will have to shop for the cheapest long-distance call the same way you can now shop for the cheapest telephone to make that call.
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