The San Francisco Bay area last October

When we shopped for two dozen smart phones we suggested at 12 retailers in the San Francisco Bay area last October, the carrier stores for AT&T, Sprint, T-Mobile, and Verizon had the highest prices for more than three-quarters of the phones. We've found phones to be especially inexpensive at Costco. Nevertheless you may not find the exact model you want there-or at any retailer in this respect. All retailers don't sell phones for all carriers, and all models might not be available everywhere.

With savings that in the main ranged from $10 to $40 a month over pricier rivals just as Verizon and AT&T, some of those carriers not surprisingly received higher reader marks for value in our service Ratings. However not every high-scoring carrier had the best prices, and you may not find many, if any, of the hottest smart phones in the model lineup of smaller and prepaid carriers.

3. Use alternative services. Bypassing the carrier and using third-party services for texting and voice calls can be a money-saver. However there are trade-offs. Text messages, including a maximum 160 bytes of data, are outrageously priced à la carte by the carrier at 10 cents each. International texts and texting during abroad can cost more-about 20 to 50 cents per message.

New apps just as Heywire and TigerText let you send text messages free over your data connection. Typically you use a special receiving phone number assigned to you by the service to avoid charges on your cell number. With most carriers, that means you won't have to pay your carrier 10 cents a pop or $5 to $30 a month for limited-to-unlimited messaging plans.

We tried both services on Android phones. Heywire worked fast and intuitively, and it's free-provided you accept fairly unobtrusive ads along the bottom of the message-thread page. However TigerText, whose selling points include private messages that self-destruct afterwards a certain time, didn't work for us.

Skype Mobile lets you make free voice calls to other Skype subscribers in the U.S. and worldwide using your smart phone. That's especially helpful for international calls, which tend to be even pricier on cell phones than on landlines. Skyping uses your carrier's data service, so such calls don't count against your cell plan voice minutes, nevertheless these VoIP (Voice over Internet Protocol) calls eat data at the rate of about 3 megabytes per minute. If you use Skype over a Wi-Fi network in other words than on the carrier's network, you don't cut into your monthly metered data allocations.

4. Max out on Wi-Fi. Avoid using your plan's allotment of data by tapping into the rising number of Wi-Fi networks that are available. Your home and work networks are obvious choices. However your cable company or Internet service provider might offer access to its own free, local Wi-Fi hotspots with your subscription, as does Time Warner Cable around the New York/New Jersey metro area and Comcast in the Philadelphia/New Jersey area.

There's another way to limit data use on 4G phones, where faster network speeds can eat up your allotted monthly data more quickly. If you find that 3G speeds are such as good as 4G for activities just as texting or streaming music, set your 4G phone to connect only to 3G.

5. Investigate employee discounts. AT&T, Sprint, T-Mobile, U.S. Cellular, and Verizon offer discounts to the employees of companies that use their service. To see whether you qualify, Google the carrier's name and "employee discount," and navigate to the Web page that asks for your work e-mail address. Discounts can be as high as 20 percent, although some deals exclude the iPhone or certain service plans.