On the wireless side, carriers typically don't even make specific promises beyond, say, Verizon Wireless' assertion that downloads from its new fourth-generation network, LTE, offer "movies in minutes" and "photos in seconds." Or AT&T Mobility's promise that the carrier "is seeing network speeds up to approximately 6 Mbps," or megabits per second.
Complicating the picture further is the intermittent rollout of system upgrades - improvements that, ironically, can leave tech aficionados behind. You say you own Verizon's latest Apple iPhone 4? Great, but it won't work on Verizon's LTE network.
So how do you know what speeds you might experience? One way is to examine the charts you find here that offer a snapshot of the Philadelphia area's wireless landscape. It was taken last month by a Seattle company, RootMetrics, that is trying to build a business by laying out the hard facts about who's up, who's down, who blocks or drops more calls, and who will make you wait longer to get and watch a video of your daughter's basketball game.
RootMetrics measures wireless performance in two ways. One is through crowd-sourcing: It invites consumers to install free iPhone or Android apps that test each carrier's performance. At www.rootmetrics.com, you can find the results: detailed service-quality maps for Philadelphia and other places around the country.
The other is professional testing, which RootMetrics CEO Bill Moore likens to the data collection done for years by the carriers themselves. One big difference, he says, is that the carriers test largely for internal reasons, to find gaps in coverage or to justify marketing claims. RootMetrics is putting its results out for everyone to see - including the report due to be released Thursday on Philadelphia, the 13th city to get RootMetrics' professional tests.
In Philadelphia, Verizon's system is the data king, thanks to its continuing rollout of LTE. Its average download speed was about 10 Mbps - fast enough, RootMetrics says, to download a TV show in 5 to 10 minutes.
Second-place Sprint's and third-place AT&T's download speeds averaged about 3 Mbps, so that TV show might take 20 minutes to download. At T-Mobile's average of about 2 Mbps, you could be waiting a little longer.
The good news is that many data-heavy tasks, such as streaming audio or YouTube-quality video, should work fine even at the lower speeds. But high-definition video might require some rebuffering along the way. RootMetrics says only that Verizon's average speeds are fast enough to avoid that or the occasional dropped frame.
Are there complications to these data? Absolutely.
One is that the testing is done with off-the-shelf Android phones made by the two leading manufacturers, Samsung and HTC, and that phone hardware and software can affect performance.
"There's no common phone across all carriers," Moore says. "We take the phone that will perform best on each network."
Another complication is the staggered rollouts of new technologies. Right now, an iPhone user will get higher data speeds on AT&T's network than on Verizon's. If a future iPhone works on LTE, Verizon's iPhone performance could leapfrog AT&T's - till AT&T installs the LTE network it, too, has promised.
Yet another complication is inconsistency in each carrier's coverage. Moore says Sprint, which uses Clearwire's WiMax system for data whenever it's available, showed speeds up to 9.8 Mbps in Philadelphia-area testing but suffered because of areas where WiMax was unavailable. On the other hand, big speed variations were common in RootMetrics' tests: T-Mobile's downloads hit 13.7 Mbps, and AT&T's 10.8 Mbps. But Verizon still led the pack, maxing out at 33.8 Mbps.
When it comes to texts, T-Mobile outpaces the competition, getting them to other T-Mobile users in less than 5 seconds and to others in 9. But on old-fashioned phone performance, RootMetrics calls the local contest a draw.
Verizon had the most blocked calls (failed to connect), and AT&T had the most dropped calls, but the problems were rare: About 1 in 200 Verizon calls failed to connect, and AT&T dropped 1 in 50 calls - though the test protocol only tried to keep the connection for two minutes.
In that, Philadelphia scored exceptionally well, Moore says: "These were some of the lowest call-failure rates across all the carriers - less than we've seen in other markets."
Contact columnist Jeff Gelles
at 215-854-2776 or email@example.com.