Messaging is the most popular data feature associated with cell phones. Several carriers recently raised the per message charge from 10 to 15 cents. That, combined with a rapid increase in smartphones (with full keyboards) targeted to consumers, may lead to unexpectedly high bills for many consumers.

Text Messaging The most popular of non-voice services, text messaging lets you use your phone's keypad (or QWERTY keyboard, if available) to send short messages to other cell phones. Usually, there is a charge (15 cents is common) both for sending and receiving these messages. Most carriers offer bundled packages, which can range from about 100 messages, all the way up to unlimited. Expect to pay $5 to $15 a month for a bundle of text-only messages, although in some cases your carrier may offer text messaging with other data services as part of a package.

Premium Messaging Premium messaging is text messaging that incurs a surcharge. A good example is the voting associated with reality TV shows. For these messages, you'll pay a flat fee, usually around $1. If you don't have a messaging bundle from your carrier, you'll also incur the per-message charge, usually about 15 cents.

TIP In most cases (all cases in which a sweepstakes is involved), the sponsor of the text program will offer a free method of voting or entering, usually via the Internet. Take advantage of this, particularly if you want to vote or enter multiple times, because premium text messages can quickly add up on your bill. Besides, why pay for something that you can have for free?

Picture and Video Messaging Picture messaging allows the upload of photos taken with your cell phone to a computer or another cell phone. Unlike text, where messages can be sent across carriers, picture transmission is usually limited to subscribers of the same carrier.

Many phones also have picture caller ID, letting you “put a face with the name,” so to speak. You can also use one or more of your photos as a screen saver. This is a feature of your phone and not a feature of your service plan. In other words, if your phone has this capability, you can use it for free.

Some services also support the ability to send short videos from your phone to an e-mail address. Longer videos can become difficult to send, due to the size of the files.

Instant Messaging Mobile versions of common instant messaging (IM) programs, such as those from AOL, Yahoo, or MSN, let you communicate instantly with friends and family. When these services are enabled on your phone, your status will appear as online to your friends, just as if you were at a PC.

TIP If you choose to enable instant messaging on your phone, you will want to make sure that you have subscribed to unlimited text messaging. Each IM, even one as simple as “LOL,” counts as a text message. It isn't hard to see how IMs can quickly grow into the hundreds, becoming quite costly if paid on a per-message basis.