There are essentially two types of cell phone coverage: analog and digital. Calls made on digital networks are clearer, more secure, and more feature-rich than calls made on analog networks. Because analog technology has been in use since the 1980s, virtually every part of the country where people live has analog coverage. Carriers have deployed digital technology more recently and, therefore, digital service plans and coverage tend to be available in the more populated and highly-traveled areas of the country. The FCC estimates approximately 97% of the U.S. population lives in counties that have some digital coverage. Significant portions of the countrys land area do not have access to digital service. Carriers are constantly upgrading their networks to expand the areas where they can offer digital mobile telephone service.
During the 1980s, the FCC licensed cellular spectrum in the 800 MHz band to two cellular carriers in virtually every market in the country. These carriers began building out their networks and offering analog cellular service. In 1994 the FCC began auctioning additional mobile telephone spectrum in the 1900 MHz band for Personal Communication Services (PCS). The carriers who purchased this spectrum began building out digital technology and offering digital mobile telephone services. Cellular carriers in the 800 MHz band have upgraded most of their networks from analog to digital technology in order to expand capacity and improve the quality of service. During the late 1990s, carriers operating in spectrum bands allocated for Specialized Mobile Radio (SMR) service began upgrading their networks with digital technology and offering mobile telephone service in competition with cellular and PCS operators. Mobile telephone carriers using these various spectrum bands continue to deploy digital technology in their networks today.
Coverage refers to the geographic area where mobile telephone subscribers can use their cell phones*. Cell phones must be able to receive or pick up a signal from a mobile telephone carriers network. Coverage varies by carrier and is determined by the extent to which carriers have built out their networks.
*The term cell phones generally refers to all mobile phones that operate on any of the three types of mobile telephone spectrum: cellular, PCS, or digital SMR.
This is determined mainly by where your carrier owns spectrum licenses and where it has built out its network within its license areas. Analog networks cover almost every area of the country, whereas digital networks, while extensive, are not everywhere. The extent to which individual carriers have built out their networks in a given market varies.
Even if your carrier has not built out its network in a given area, you may be able to connect to or roam on another carriers network. If your carrier has an agreement with another carrier, and if you have a type of handset that allows roaming, you may be able to connect. (See The Handset, page 3.) Most handsets that allow roaming have an indicator to let subscribers know when they are outside their home calling area and/or out of reach of their carriers network. How much you will pay for calls in different areas depends on your pricing plan.
Even where a carrier offers coverage in a specific geographic area, you may not be able to complete a given call due to limitations in network architecture and capacity. When a carrier fails to hand off a call in progress, as you travel from one part of the carriers network to another, a dropped call results. When many customers use a carriers network at the same time, its capacity becomes constrained. Other customers trying to connect will hear a busy signal instead of being able to complete their calls.
Topography can also affect coverage, causing dead spots. A dead spot is an area where service is not available because the signal between the handset and the cell tower is blocked, usually by hilly terrain, excessive foliage, or tall buildings. Carriers are constantly improving and upgrading their networks in order to minimize these types of problems.
Coverage is also affected by the type of mobile telephone handset a user owns. Single-mode phones can connect to either a digital or an analog network but not both. Dual-mode handsets can be used on both analog and digital networks. Tri-mode handsets can be used on analog and two types of digital networks. The more networks your phone can be used with the better chance you have to pick up service nationwide. The strength of the antenna and quality of the engineering in a mobile handset can also affect your ability to pick up a certain type of signal or any signal at all.
Coverage maps are meant to give users a general idea of where their phones will work when outside or in a car. However, carriers network signals often fade inside buildings or in underground locations such as basements, parking garages or subways. Carriers are increasingly putting special facilities inside some of these areas to enhance coverage, but they are by no means universal. Therefore, you should not necessarily expect to be able to use your phone in these types of locations.
Carriers provide coverage maps on their Web sites and in stores where their products are sold. However, these maps carry the disclaimer that they are provided for informational purposes only and that actual coverage may vary from what is displayed on the map. Reasons for this variance include the dynamics of topographical and network capacity constraints on any given day.
Source: Federal Communications Commission, Consumer & Governmental Affairs Bureau