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The votes are in: Which mobile data provider is best?

Find out which carrier gets the most cheers -- and which the most jeers -- from our 2015 survey respondents.

What's most important about your smartphone? Something you don't actually see — the network you use to connect to the Internet, find and use apps, get information and more. So for the third year in a row we set out to discover which mobile service provider gives you the most comprehensive and reliable data network coverage, the fastest upload and download speeds, and the most bang for the buck.

To do it, we checked with those who know the most about using the networks — you and other Computerworld readers. We conducted a 12-week-long online survey in the summer of 2015 asking smartphone users to rate their providers in a variety of categories: average upload speeds, average download speeds, availability of connection, reliability of connection, performance relative to cost, technical support, selection of phone models, customer service/billing, and more.

Survey-takers had five choices for each category: very satisfied, satisfied, neither satisfied nor dissatisfied, dissatisfied and very dissatisfied. We crunched the numbers from our 870 respondents and came up with the winners and the losers.

The vast majority of our survey respondents — 90% — use one of the four most popular U.S. cellular service carriers: 36% use Verizon Wireless, 30% use AT&T, 15% use T-Mobile and 9% use Sprint. While those are the only providers we rated in this story, we used all survey responses (including those from customers of smaller carriers) when tallying overall satisfaction results, mobile data use and other general statistics. (For detailed information about the survey and how we crunched the numbers, see "How the survey was conducted and graded.")

We asked a lot of other questions as well, such as what activities people use mobile data networks for, how much they pay for their service, if they've unlocked their phones, whether they plan to buy a wearable device, why they chose their mobile provider, if they believe their carrier protects their private data, and more. Using that information, we've put together a comprehensive snapshot of mobile data use and satisfaction.

We found, for instance, that even though new phone-unlocking rules generated lots of headlines in 2015, very few respondents actually unlocked their phones. And even though the Apple Watch was released in 2015 with the usual Apple hype and hoopla, only 20% of respondents are considering buying a wearable in the coming year. (Of those planning to buy, though, nearly half said an Apple Watch would be their choice.)

We found out lots more, with plenty of surprises along the way. Read on for those details — or click here to skip ahead and see which is the best mobile data provider, which the worst, and how the others fared.

Editor's note: For the sake of readability, in the story text below we've combined the "very satisfied" and "satisfied" responses into a single "satisfied" percentage, and we've likewise combined the "dissatisfied" and "very dissatisfied" responses into a single "dissatisfied" percentage. The accompanying charts show the full percentage breakdowns.

How you rate your mobile data service

Although everyone likes to complain about service providers and data networks, we found that on a whole, respondents are happier with them than they were in our 2014 survey. For example, 70% of 2015 respondents are satisfied with the availability of their data connection, up from 62% satisfied the previous year. For almost every question we asked, people are more satisfied than they were a year earlier — even when it comes to everyone's worst bugaboo, tech support, where 54% of the 2015 respondents are satisfied, versus 48% in 2014.

Let's take a closer look at each category.

Data connection availability and reliability

A smartphone is, above all, a handheld, Internet-capable computer, and so the availability and reliability of a data connection may well be the most important feature offered by a wireless carrier. So we asked how satisfied people are with their data network coverage and availability.

Overall, respondents are quite satisfied with the availability of their data connection (is the connection there when and where they want it?), with 70% satisfied and only 14% dissatisfied. The remaining 16% say they are neither satisfied nor dissatisfied. People are more satisfied with the availability of their data connection than they were when we surveyed them in 2014, when 62% were satisfied and 20% dissatisfied.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Drill down into the breakdown by carrier, though, and you see that the high satisfaction ratings are largely driven by a single carrier, Verizon, which has astonishingly high ratings — 81% satisfied and only 9% dissatisfied. AT&T was a distant second with 66% satisfied, followed by T-Mobile with 59% satisfied. Bringing up the rear was Sprint, whose customers are not a happy bunch, with 48% satisfied and 34% dissatisfied with the availability of their connection.

People are not quite as happy with the reliability of the data connection once it's made (are there dropped connections or streaming interruptions?), with 65% satisfied and 14% dissatisfied overall. Still, the numbers are up from a year earlier, when 56% reported themselves as being satisfied and 20% dissatisfied.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Once again, Verizon is the big winner, with 75% satisfied, followed by T-Mobile with 63% satisfied, then AT&T with 60% satisfied. Sprint was again the big loser, with 46% satisfied and 33% dissatisfied.

Network speed

Data connections aren't just about availability and reliability — they're about how fast data is uploaded and downloaded. People are about as satisfied with the download speeds of their service as they are with its availability and reliability, although they don't rate their upload speeds as highly.

Some 71% of survey respondents say they are satisfied with their download speed, and about 10% dissatisfied. That's well above 2014's 59% satisfied and 18% dissatisfied.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

T-Mobile is the big winner in this category, with 83% satisfied and just 5% dissatisfied, followed by Verizon with 75% satisfied, AT&T with 65% satisfied, and Sprint with 57% satisfied. All four carriers' download speed satisfaction ratings are up from the previous year.

People are not quite as pleased with their upload speeds: 62% say they are satisfied and 9% dissatisfied. That's better than in 2014, when only 52% were satisfied and 16% dissatisfied.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

T-Mobile customers are the happiest with upload speeds, with 77% satisfied and a mere 4% dissatisfied, followed by Verizon with 67% satisfied. AT&T has only a 53% satisfaction rating, and Sprint was yet again the loser, with 51% of its customers satisfied.

Value and phone selection

People are slightly more pleased this year with the overall value they get from their mobile service provider — that is, their service's performance relative to its cost — than they were in 2014, but the numbers still aren't stellar. Fifty-five percent are satisfied, while 24% are dissatisfied, compared to 50% satisfied and 30% dissatisfied a year earlier.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Among the Big Four carriers, T-Mobile is clearly the value leader. The company has a 77% satisfaction rating for value from its customers. Next in line is Sprint with a 56% satisfaction rating, followed by Verizon with 48% satisfied and AT&T with 42% satisfied. Every carrier had higher 2015 ratings in this category than in 2014.

The phone selection category gets the highest satisfaction ratings in the entire survey. Seventy-eight percent of respondents are satisfied with the selection of phones available from their carrier, and only 6% dissatisfied. That's right in line with 2014, when 76% of people were satisfied and 8% dissatisfied.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

There's no real difference in satisfaction ratings for phone selection among the major carriers: Sprint and T-Mobile are at 81% satisfied, followed by AT&T at 80% and Verizon at 79%.

Tech support and customer service

Here's a surprise: A majority of people are satisfied with their carrier's technical support this year — 54% are satisfied and only 12% dissatisfied. That's a bump up from 2014, when 48% of respondents reported themselves as satisfied and 15% dissatisfied.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

T-Mobile wins big in this category: An impressive 70% of its customers who took our survey report themselves as satisfied. It's the third year in a row T-Mobile has come out on top and represents a big leap from last year, when 54% of its customers were satisfied with the carrier's tech support. Verizon has a 52% satisfaction rate, followed by Sprint with 51% satisfied and finally AT&T with 49% satisfied.

People are generally satisfied with their carrier's customer service and billing, with 62% satisfied and 12% dissatisfied, up slightly from 56% satisfied and 15% dissatisfied a year earlier.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

T-Mobile is well ahead of the pack again, with 76% of its customers satisfied. That's followed by Sprint with 62% satisfied, Verizon with 57% satisfied and AT&T with 56% satisfied.

Switching providers? Not so much

Considering that respondents are generally satisfied with their carriers in every area we surveyed, it's no surprise that only 14% have switched carriers in the past year. Of that small group, two thirds switched once, 20% switched twice and just 14% switched more than twice. Why did they switch? Price (57%), coverage and reliability (44%) and plan options (39%) were the most frequently cited factors.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

And just 28% of respondents say they are considering switching to another provider, an even lower number than last year's 39%. The same three reasons are important to this group: 74% cited the cost of their plan as a reason for possibly switching, followed by coverage and reliability at 44% and plan options at 37%.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

These responses vary by carrier: A whopping 85% of Verizon customers and 75% of AT&T customers who are considering switching point to price, while T-Mobile and Sprint customers overwhelmingly cite coverage and reliability as reasons they might switch carriers.

Baby steps toward unlocked phones

In February 2015, regulations went into effect that require carriers to allow customers to unlock their phones if they want to switch carriers (or for any other reason, for that matter). At the same time, more consumers are opting to buy unsubsidized, unlocked phones that aren't tied to a particular carrier's contract. So we wanted to find out whether people have begun to unlock their phones or buy unlocked phones.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

The answer: Largely they haven't. Only 15% of respondents report they unlocked their phone or bought an unlocked phone in the past year. T-Mobile customers are leading the charge with 34% reporting unlocking a phone or buying an unlocked phone, well above AT&T with 12%, Verizon with 8% and Sprint with 6%. That's not too surprising, since T-Mobile has been offering no-contract services for a couple years now, while the other carriers have only recently offered that model.

Privacy and provider trustworthiness

During the last several years there have been nonstop revelations about government agencies invading people's privacy, sometimes with the help of private companies. But as was the case in our 2014 survey, people are for the most part comfortable with the way in which their carriers handle their private data.

Sixty-nine percent of respondents rate their carriers as trustworthy when it comes to protecting their data, compared to 16% who believe they are untrustworthy and 15% who say they have no opinion. That's a slight uptick in trustworthiness from the previous year, when 63% of respondents rated their carriers as trustworthy and 22% considered them untrustworthy.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

T-Mobile received the highest ratings, with 77% of customers who took our survey rating it trustworthy and 5% untrustworthy. (T-Mobile was the leader in 2014 as well, with 76% of its customers rating it as trustworthy.) There is little difference among the other major carriers, which have trustworthiness ratings ranging from 66% to 69%.

Despite those high ratings, half of respondents are more worried now about the privacy of their mobile data than they were a year earlier, 5% are less worried and 45% report the same level of concern.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Respondents cite invasive apps, high-profile data breaches in the news and ever-more sophisticated hackers as reasons to be concerned. However, only 3% of respondents say their phone has ever been compromised or hacked.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Less than half of respondents (43%) say they have changed the way they use mobile apps or mobile data in the past year due to privacy concerns, while the remaining 57% say they haven't changed their data behavior because of privacy fears. Those who have made changes cite a variety of safety measures taken, including avoiding untrusted apps and Web sites (80%); using fingerprint unlock, stronger passcodes or two-factor authentication (67%); restricting app permissions including access to location (66%); avoiding public Wi-Fi (61%); and disabling their phone's location services when not in use (53%).

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Wearable devices get passed over

Despite the hype around smartwatches and other wearable computing devices in 2015, including the release of the Apple Watch, people simply aren't interested in buying. Only 10% of respondents report having bought a wearable smart device in the past year.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Of those who did buy one, 50% bought a fitness tracker, 25% bought an Apple Watch, 23% bought an Android Wear watch, 21% bought another type of smartwatch and a mere 2% bought smartglasses.

What type of wearable device did you buy?

Select all that apply

Fitness tracker
50%
Apple Watch
25%
Android Wear watch
23%
Other smartwatch
21%
Smartglasses
2%
Source: Computerworld mobile data service survey, 2015.
Base: 87 respondents who say they have bought a wearable smart device in the past year.

When we asked if respondents were considering buying a wearable smart device in the coming year, they answered like they did the year before: They're not interested. Eighty percent say they aren't going to buy one, compared to 77% the previous year.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Of those who say they are considering buying a wearable, 49% say they're interested in an Apple Watch, 38% an Android Wear watch, 17% another smartwatch, 44% a fitness tracker and 7% smartglasses.

What type of wearable device are you considering buying?

Select all that apply

Apple Watch
49%
Fitness tracker
44%
Android Wear watch
38%
Other smartwatch
17%
Smartglasses
7%
Source: Computerworld mobile data service survey, 2015.
Base: 161 respondents who say they're considering buying a wearable smart device in the next year.

Page Break

Your mobile data use

How do you use your mobile data? Do you connect mainly to 4G or 3G networks? Is your connection suitable for regularly watching videos? Those are just a few of the questions we asked in our 2015 survey.

We found, not surprisingly, that 4G networks are now the norm for data connections, continuing a trend that we saw in our survey the previous year. Sixty percent of respondents say they connect solely via a 4G connection of some kind, while only 8% connect solely on 3G. (In 2014, some 55% connected solely via 4G, and 14% relied solely on 3G.)

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

These figures understate how widely used 4G networks have become, because 26% of people say they connect via either 3G or 4G depending on their location. That means 86% of people use a 4G network at some point.

T-Mobile customers have the highest 4G use, with 72% saying they connect via 4G and 21% saying either 3G or 4G depending on their location. Sixty-three percent of Verizon and AT&T customers connect via 4G, while Sprint customers are stuck in the slow lane — only 34% connect solely via 4G.

Because tiered-data plans are the norm, people pay attention to how much time they spend using their data connections. Only 9% of respondents say they use their data connection for more than three hours a day, 21% use it for between one and three hours, 33% use it for between 20 minutes and an hour, 21% use it for between 10 to 20 minutes, and 16% use it for less than 10 minutes. (Note that these numbers don't include the amount of time they use Wi-Fi connections.) These percentages are almost precisely what we found last year, and closely align with what we found in 2013 as well.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

The numbers vary by carrier, though, with 43% of Sprint customers using a data connection for more than an hour each day (probably because of the preponderance of unlimited plans among Sprint customers) and only 29% of AT&T customers using it for more than an hour.

Thirty-eight percent of respondents say they used their phones more for business in 2015 than in 2014 for activities such as checking work email, using productivity apps and accessing data in the cloud. Only 10% say they're using their phones less for work. The rest say business use is unchanged.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Only 21% of respondents who use their personal smartphone for work are fully or partially compensated for their expenses by their employer, and only 37% say their employer has a formal policy regarding the use of smartphones at work.

What do people use their data connection for? Four activities are cited by more than half of respondents: emailing by 70%, Web searches and browsing by 64%, GPS navigation and maps by 61%, and getting local data (weather, business hours/ratings, transit info, etc.) by 51%. Only two other activities break the 30% mark: reading news with 38% and using social media with 34%.

What do you primarily use your mobile data connection for?

Select your 5 most frequent activities

Emailing
70%
Web searches and browsing
64%
GPS navigation (maps, directions)
61%
Getting local data (weather, business hours/ratings, transit info, etc.)
51%
Reading news
38%
Social media
34%
Streaming and downloading music, videos or, podcasts or books
20%
Banking
19%
Using cloud storage/productivity tools (notes, tasks, calendars, contacts, etc.)
19%
Uploading and downloading photos
16%
Using your phone as a mobile hotspot
14%
Downloading apps
11%
Shopping
10%
Playing online games
9%
Making VoIP calls
7%
Other
3%
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

The use of mobile phones for watching video seems to be growing, albeit slowly: 27% of people say they're watching more videos than a year ago, and 13% are watching fewer, with 60% saying their video-watching has stayed the same. That said, only 20% of respondents use their mobile data connection to stream or download music, video, podcasts or books. When they do, it seems to work pretty well: 24% of respondents say their mobile network is always fast enough for watching video, 58% say it's fast enough most of the time, and 18% say it's sometimes fast enough. Less than half of 1% say it's never fast enough.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Plans, contracts and costs

For the third year in a row, family plans are far more popular than any other type: 48% of survey respondents are on family plans, 27% are on individual plans, and the rest are almost evenly split between data-sharing plans that include other devices such as tablets (13%) and business plans (12%). The numbers almost precisely mirror the results for 2014 and 2013, with the slight exception that for the first time data-sharing plans were more popular than business plans.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Long-term contracts are slowly on the way out. Under the old model, carriers subsidized the cost of premium smartphones up front and made that money back by locking customers into a pricey two-year contract. With increasingly popular no-contract plans, however, you pay the full price of the phone but are free to leave your carrier without facing a stiff penalty. T-Mobile moved to a no-contract service model years ago, and in 2015, Verizon, Sprint and AT&T began moving away from contracts as well.

Because these changes are recent for three of the big carriers, many of our survey respondents still have long-term contracts, but those numbers are dwindling. Some 61% of 2015 respondents are on contracts and 39% on month-to-month plans. In 2014, 65% were on long-term contracts, and the year before that a whopping 84% had long-term contracts. We expect that contract number to continue to drop every year as customers' current contracts expire.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Here's a piece of no-news: Unlimited data plans are also becoming a thing of the past. Thirty-nine percent of respondents say they are on unlimited plans and 55% on tiered plans. (The rest are not sure what kind of plan they're on.) In our 2014 survey, 42% said they were on unlimited plans and 50% on tiered contracts. And in our 2013 survey, 56% of respondents said they were on unlimited plans and 40% on tiered plans.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

Sprint and T-Mobile's attempt to differentiate themselves by offering unlimited data plans seems to have paid off, particularly at Sprint, where 78% of respondents say they have unlimited data. At T-Mobile, 65% say they have unlimited data plans. Only 27% of Verizon customers and 31% of AT&T customers say they have unlimited plans.

Almost everyone who responded to our survey has voice-and-data bundles rather than data-only plans, with 81% having the bundles and 19% having data service only. Those numbers are almost identical to our findings for 2014.

In the data-only group, 40% of respondents say they pay $40 or less for service each month, 26% pay between $41 and $80, and 25% pay more than $80. The rest are not sure how much they pay. Those numbers vary by carrier. Fifty-two percent of T-Mobile customers who took our survey pay $40 or less for data only, along with 50% of Sprint customers, 36% of AT&T customers and 29% of Verizon customers.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 169 respondents.

Unsurprisingly, those with bundled voice and data have higher monthly bills. Twenty-two percent pay $60 or less per month, 26% pay between $61 and $100, 20% pay between $101 and $150, and 28% pay more than $150. Five percent aren't sure how much they pay. Sprint and T-Mobile customers also have the lowest bills for bundled service: 45% of Sprint customers pay $80 or less, as do 42% of T-Mobile customers. Only 25% of Verizon customers and 22% of AT&T customers pay that amount.

Mouse over each pie slice to see its value.
Source: Computerworld mobile data service survey, 2015. Base: 702 respondents.

Why you chose your mobile provider

How do people choose which mobile provider to use — is it price, coverage, plan options, the availability of a specific phone? Did they want a no-contract plan, or did their employer choose the carrier? We asked survey respondents to rank the importance of eight factors, with 1 being the most important and 8 being the least important.

For the second year in a row, network coverage was the most important factor, with 66% of respondents ranking it either No. 1 or No. 2. Next was price, with 53% ranking it 1 or 2. Many people simply don't want to go through the bother of switching: 42% gave a 1 or 2 ranking to staying with their existing carrier simply because they are longtime customers. Specific plan options played a lesser role, with 33% of respondents giving that a ranking of 1 or 2. The rest of the factors come in about equal, with roughly a quarter of respondents indicating that the availability of a no-contract plan or a specific phone was an important factor in their decision, that their employer selected the carrier, or that they're happy with their current carrier and have no reason to switch.

Did you choose your carrier based on...

Percentage of respondents who ranked each reason 1 or 2, where 1 is most important and 8 least important

Coverage
66%
Price
53%
Longtime customer
42%
Plan options
33%
Wanted a no-contract plan
28%
Company selected
28%
No reason to switch/happy with service
28%
Specific phone
25%
Source: Computerworld mobile data service survey, 2015. Base: 870 respondents.

We asked people to write in other factors that influenced their decision. Common responses include getting a discount from their workplace, the quality of customer service offered by the carrier, and the ability to use their phone and service when traveling abroad.

The rankings: Best and worst mobile data providers

So which data providers have the most and least satisfied customers? We used weighted averages on a scale of 1 to 5, did some number-crunching, and came up with the results. (See "How the survey was conducted and graded" for details.)

T-Mobile is the clear favorite among 2015 survey respondents, just as it was in 2014. In 2015 it had the top rankings for five of the eight categories, and topped the field with a weighted rating of 3.94 out of 5. At 3.75 overall, Verizon placed second. Next came AT&T with a 3.57 rating, followed closely by Sprint with a 3.54. In 2014, AT&T placed second, Verizon third, and Sprint trailed the other three.

T-Mobile dominated many categories, but one stood out above all others: performance relative to cost — in other words, bang for the buck — where it had a 4.1 score, far ahead of second finisher in that category, Sprint, which had a 3.5 rating. Verizon was third in the category, at 3.3, and AT&T had 3.2.

This is the third year in a row that T-Mobile's flexible pricing strategies, including its no-contract, no-phone-subsidy plans, appear to have paid big dividends in the value category — so it's not surprising that the other major carriers are now following in T-Mobile's footsteps with similar offerings for no-contract, no-subsidy plans.

In the 2015 survey, T-Mobile also led the ratings for average upload speeds (with a rating of 4), average download speeds (4.1), technical support (4) and customer service/billing (4). Given that it did so well in both the network performance categories and the softer categories of dealing with customers, it's no surprise that it was ranked so high in performance relative to cost.

Verizon, as in years past, did well in the network performance categories, coming in first for availability of connection (4) and reliability of connection (3.9). It also came in second to T-Mobile in average download speeds (3.9) and average upload speeds (3.8).

Sprint won only a single category, phone selection, with a 4.2 rating, barely ahead of its rivals. The best AT&T could muster, meanwhile, was a second-place finish for availability of connection (3.7); it came in third or fourth in all other categories.

Note: If you'd like to see the raw figures we used to calculate these ratings, download our survey results PDF.

download
Download the results of Computerworld's 2015 mobile data service survey to see how readers rate AT&T, Sprint, T-Mobile and Verizon on network speed, value, tech support and more. Computerworld

Bottom line

Top rankings are important for more than bragging rights — companies that get high marks tend to do well in business as well. That was true of T-Mobile in 2015. By the middle of the year, it had surpassed Sprint in total subscribers, although at 61.2 million subscribers, T-Mobile still lags far behind Verizon with 137.6 million subscribers and AT&T with 126.4 million.

T-Mobile gained subscribers over the last several years in part because it's been a pioneer in eliminating long-term contracts and subsidized phones. Its competitors followed suit in 2015: Verizon stopped subsidizing phones and began moving away from contracts, and AT&T has been doing the same thing. Sprint joined the party in 2015 as well. So we'll have to see whether that blunts T-Mobile's growth in 2016.

Another reason for T-Mobile's growth spurt is the company's aggressive expansion and improvement of its network in recent years — something Sprint has been concentrating on as well. It shows: After conducting nationwide performance tests of the four major carriers' networks in the second half of 2015, testing firm RootMetrics declared that all four networks are strong. Although Verizon came in first for network reliability, network speed, data performance, call performance, text performance and overall performance, RootMetrics noted that Verizon's overall performance score of 94.5 out of 100 wasn't far ahead of the others' scores of 91.3 (AT&T), 86 (Sprint) and 80.9 (T-Mobile).

When Sprint looks to the future, however, it may see dark days ahead. Our survey results show that it's been the least-loved carrier for years, and the subscriber numbers show that it's now the least popular as well. Back in 2014 there was talk of a merger with T-Mobile, but the Obama administration made clear it preferred the competition of having four major carriers, not three, so the deal was nixed. But there will be a new administration in 2017. If Sprint continues to slip, don't be surprised to see merger talk spring up again.

Perhaps the biggest wireless news of the year was that carriers must now legally allow phones to be unlocked by consumers, so consumers can now move with them from one carrier to another. That, plus the ending of phone subsidies and the slow death of long-term contracts, puts pressure on all four carriers to deliver a better data network and better customer service if they want to thrive, because no longer can they count on customer lock-in via long-term contracts.

One way carriers are hoping to differentiate themselves is by allowing customers unlimited data for certain services, even as they hold onto tiered plans. T-Mobile's Binge On service, for instance, offers some customers unlimited video streaming from various content providers — Netflix, HBO GO, HBO NOW, Showtime and Hulu, among many others. AT&T and Verizon, meanwhile, have announced sponsored data services that allow customers access to content, websites and apps from certain providers without being charged for data; these programs also let consumers accumulate free data by taking surveys or clicking on ads. However, allowing unlimited streaming from certain providers only might violate Federal Communications Commission net neutrality rules, and the agency has written to both T-Mobile and AT&T asking for more details about their offerings.

It all adds up to what could well be a wild 2016 in the wireless world. Check back often for Computerworld's wireless coverage. And, of course, we'll do our annual mobile data provider survey next year as well.