( CNN ) -- Mobile devices are only as good as the networks that serve them . But too often , a mobile user will purchase a new smartphone with a two-year carrier contract , only then to learn that the phone gets lousy reception at home , work or school . That 's why the first -- and obvious -- question consumers should ask themselves when considering a mobile phone is this : Which carriers get the best service in the places where I spend most of my time ? The trouble : This is n't always an easy question to answer . Yes , carriers all provide coverage maps on their websites that show where their networks are supposed to reach -- theoretically , based on cell phone tower locations . But , in reality , signal strength and network speed can vary substantially due to terrain , structures , the typical amount of data-hungry wireless devices on the network in a given location , and other factors . When looking for a new carrier , some people attempt to gauge the local quality of a network by finding local customers of various carriers and asking them how many signal bars they generally see on their phones . However , this is n't necessarily reliable , since ( as I wrote last year ) signal bars are largely meaningless , and they 're sometimes misleading . This is where crowdsourcing can help : Mobile users can work together to create crowdsourced maps that show how well wireless networks really perform in specific locations . Here are two projects that you can actually contribute to , by sending data from an app on your smartphone : . Open Signal Maps . This project , by Staircase3 , collects data via an Android application . As you are out and about , this application runs in the background , monitoring the signal strength of your carrier 's network . If you have data-sharing turned on for the app ( you can turn it off ) , your data are stripped of identifying information and uploaded to Staircase3 's servers . Aggregate user data are displayed on maps on the Open Signal Maps site . I 've installed this app on my Droid Incredible , and it 's interesting and useful . In addition to showing the direction and location of the tower my phone is connected to , and signal strength , it allows me to conduct network speed tests . This is important because both signal strength and network speed play important roles in the quality of voice calls and data connections . According to the Open Signal Maps blog , `` A high ( signal strength ) does not guarantee a good connection . You can be communicating really well with the tower but the tower might be choked up -- it might be dealing with so much network data that you get terrible speeds . '' Also , being able to easily conduct your own network speed test can indicate whether your carrier might be `` throttling '' your data connection , as Verizon recently said it will start doing to the top 5 % of its customers by data usage . The coverage maps on the Open Signal Maps site appear to offer data for major and minor carriers in most regions . They do n't offer an iPhone app , because of differences in how the iOS operating system captures signal data . A BlackBerry app is under consideration . RootMetrics . This project collects data via an iPhone app . Android and BlackBerry apps are coming , the site says . The maps on the RootMetrics site allow you to compare the performance of AT & T , Verizon , Sprint and T-Mobile networks . Smaller carriers , such as US Cellular or MetroPCS , are not shown . These maps are a bit simpler to interpret than the Open Signal Maps , and they have user-friendly features . For example , they express network speed as the number of seconds it takes to upload or download a song . RootMetrics users also can view their own personal map with a history of signal strength and network speed . Both of these projects are most useful in major metro areas where lots of people use smartphones . They encourage people to use their apps in other locations to help make their maps more complete . Although people who use feature phones ( the next step down from smartphones , used by nearly 75 % of U.S. mobile users ) can not run the apps for these projects , the data on these maps still might be useful for selecting a local carrier . In the big picture , projects like these could help hold carriers accountable for the network speeds they advertise , an issue that 's likely to become especially contentious in the next few years as carriers struggle to deliver high-speed wireless broadband to a fast-growing number of data-sucking phones . As Mashable notes , `` Finally , we 'd have a source of real-world information to counteract the questionable maps we see from wireless providers . '' The opinions expressed in this commentary are solely those of Amy Gahran .
Company maps of wireless networks can be inaccurate or lacking detail . Application designers have turned to crowdsourced data . Open Signal maps has an app for Android . RootMetrics has an app for iPhone ; Android and Blackberry versions coming .