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This chapter is from the book

Connecting to the Internet via a Cellular Data Network

Most cell providers for the iPhone also provide a wireless Internet connection that your iPhone uses automatically when a Wi-Fi connection isn’t available. (The iPhone tries to connect an available Wi-Fi network before connecting to a cellular Internet connection.) These networks are great because the area they cover is large and connection to them is automatic. And access to these networks is typically part of your monthly account fee. You can typically choose various amounts of data per month for different monthly charges. The best case is where you have unlimited data, but this type of data plan is typically fairly expensive and they are becoming more rare.

Sometimes, the performance offered by these networks is less than ideal; in other cases, the performance is very good. The performance can also vary by your location within the network as well, so you mostly just have to try your Internet applications to see what kind of performance you have in any location.

Some providers have multiple networks, such as a low-speed network that is available widely and one or more higher-speed networks that have a more limited coverage area. Your iPhone chooses the best connection available to you so you don’t have to think about this much. However, if you connect to a low-speed network, you might find the performance unusable for web browsing or other data-intensive tasks; in which case, you have to suffer with it or connect to a Wi-Fi network.

In the United States, the iPhone providers are AT&T, Verizon, and Sprint; all offer high-speed 3G cellular networks. In other locations, the names and speed of the networks available to you might be different.

The following information is focused on a 3G network because I happen to live in the United States. If you use another provider, you are able to access your provider’s network similarly, though your details might be different. For example, the icon on the Home screen reflects the name of your provider’s network, which might or might not be 3G.

AT&T’s 3G high-speed wireless network provides reasonably fast Internet access from many locations. (Note: The 3G network is not available everywhere, but you can usually count on it near populated areas.) To connect to the 3G network, you don’t need to do anything. If you aren’t connected to a Wi-Fi network, you haven’t turned off 3G, and your iPhone isn’t in Airplane mode, the iPhone automatically connects to the 3G network if it is available in your current location. When you are connected to the 3G network, you see the 3G indicator at the top of the iPhone’s screen.

Whenever you are connected to the 3G network, you can access the Internet for web browsing, email, and so on. While the speed won’t be quite as good as with a Wi-Fi network, it is relatively fast, certainly enough to be usable.

While the 3G network is fast, it does come with a price, which is shorter battery life. If you want to disable access to the 3G network or to any cellular data network to increase the amount of time between charges, perform the following steps.

  1. Move to the Settings screen.
  2. Tap General.
  3. Tap Network.
  4. To disable all cellular data connections, tap ON next to Cellular Data. Its status becomes OFF and the iPhone is no longer able to connect to any cellular data networks.

To restore your access to the cellular data network, move back to the Network screen and slide the Cellular Data switch to the ON position by tapping it.

When you move outside of your primary network’s coverage area, you are in roaming territory, which means a different provider might provide both cellular phone or data access or both. The iPhone will automatically select a roaming provider if there is only one available or allow you to choose one if there are options.

When you roam, roaming charges can be associated with calls or data exchanges that happen. These charges are often quite expensive. The roaming charges associated with phone calls are easier to manage given that it’s more obvious when you make or receive a phone call. However, data roaming charges are much more insidious, especially if Push functionality (where emails are pushed to iPhone from the server as they are received) are active. And when you use some applications, such as Maps to navigate, you don’t really know how much data is involved. Because data roaming charges are harder to notice, the iPhone is configured by default to prevent data roaming. When data roaming is disabled, the iPhone is unable to access the Internet when you are outside of your network, unless you connect to a Wi-Fi network.

If you want to allow data roaming, move to the Network screen and tap the Data Roaming OFF button. Its status becomes ON, and when you move outside your primary network, data will come to iPhone via the available roaming networks. This can be very, very expensive, so you should disable it again by tapping ON as soon as you’re done with a specific task.


Generally, you should avoid allowing data roaming unless you are sure about its cost. You have no control over this and won’t really know how much it will be until you get the resulting bill, which can sometimes be shocking and painful.

When a Wi-Fi or faster cellular network isn’t available, you are reduced to using the slower cellular data networks available to you. For AT&T, this is called the EDGE network. (The original iPhone could only use Wi-Fi or the EDGE in the United States.) When no better network is available (assuming Cellular Data isn’t disabled and the iPhone isn’t in Airplane mode), the iPhone connects to the slower network automatically, so you can still use its Internet functionality.

There’s often a good reason that a slower network, such as the EDGE, is the last resort; the speed is sometimes so slow that you’ll need much more patience than I have to use the Web.

In the United States, the EDGE network can work okay for email and some of the other less data-intensive functions, however. And sometimes an EDGE connection is better than no connection at all. When iPhone is connected to the EDGE network, the E icon appears at the top of the screen; if you use a different provider, you see the icon for that network instead.

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