The websites of individual service providers including Verizon, AT&T and T-Mobile display area coverage maps for their wireless calling plans. Other sites, such as Sensorly.com and OpenSignal.com, compare wireless network access in specific locations throughout the United States.
Verizon, America's largest 4G LTE service provider as of May 2015, claims to provide coverage to 98 percent of the United States, according to Verizonwireless.com. Verizon customers can use the website's search feature to find coverage areas for specific services, including data, voice and messaging, and 4G LTE.
AT&T, claiming to cover 99 percent of Americans, offers similar search features for its voice, data or GoPhone services on Att.com. In addition to displaying different types of coverage, service maps at T-Mobile.com show verified wireless connections by T-Mobile customers.
Both Sensorly.com and OpenSignal.com provide location-specific coverage maps that compare access among wireless services of a region's top cell phone providers. Sensorly.com relies on data from a network of connected Sensorly users to carry out speed tests and create and share service performance maps for a specific provider. OpenSignal also collects data through its users' mobile apps, but this website displays the current signal strength of competing networks within a region and shows nearby cell towers that can ensure more consistent coverage for some wireless services.