Could it possibly make financial sense not to install a normal phone in your house and to rely exclusively on a cellular phone instead? It depends on many factors, of course, but amazingly the answer is often yes.

Sprint PCS offers a mobile phone line with voice mail, call waiting, caller ID, and call blocking, and 500 minutes of combined local and long distance calls for $50 per month. Additional minutes cost 25 cents each. Or you can pick a plan with 1500 minutes of calls for $149. In Seattle, where Explainer lives, the local phone company charges $16 for the phone line, $7 for voice mail, and $3 for call waiting. And Explainer has a 10c/minute long distance plan from AT&T with a $5 monthly surcharge.

Let's look at an actual phone bill Explainer received the other day. Explainer estimates he made or received about 100 minutes a month of local calls (which are free) and received 100 minutes of long distance calls, and he paid for 200 minutes of long distance calls. This pattern costs $61 from the local monopoly but would cost only $50 on a cell phone. If Explainer made and received 400 minutes of long distance calls per month, not only would his mother be pleased, but he'd save $21 dollars relative to a land line. And if he used 500 minutes a week, he'd still save $6.

Your results may vary. If you make lots of local calls and very few long-distance calls, the traditional phone may win since local calls are itemized on the cell phone. If you have a family and need multiple extensions, there's no such thing with cell phones, so you'd need to get entirely separate lines. You need to buy the phone: cell phones are more expensive ($99 for the cheapest one from Sprint), but there is no startup fee, whereas the installation and wiring for a traditional phone can be pricey.

Modem users will be disappointed to hear that a cell phone will not support the use of an ordinary modem. But in Seattle, at least, you can get a regular phone line stripped of call waiting, etc., for only $16 a month. So if you save more than $16 by using the cell phone for your calls, you can have a regular line just for your modem and still come out ahead.

If your long-distance charges are roughly like mine, here's how to tell if you can save some money by switching exclusively to a cell phone.

1. Add up the monthly cost of local phone service, the surcharge on your long-distance deal, and any extras you have (like voice mail, caller ID , etc ...). For instance, Explainer pays $31 dollars a month for a phone in his apartment with voice mail, call waiting, and a 10-cents-a-minute calling plan.
2. Estimate how many minutes of local calls you make and receive per month, and divide by ten.
3. Estimate your total average phone bill--including long distance charges and assuming you pay for incoming calls.

If (1) is greater than (2), and (3) is close to either $50 or $150, you'll probably save money by going cellular.

Note: Explainer does not receive any money or support from any cell phone provider. After researching this article, however, he is considering getting one.

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