Skip to main content

A talk with T-Mobile about those new maps I complained about

Yesterday I spent some time talking with Grant Castle, T-Mobile's VP of Engineering and QA to better understand the way the data in those maps is sourced.

Mr. Castle took my pointed criticism in stride; he's accustomed to it, working as he does for telecom's most outrageous, salty CEO.

Mr. Castle admitted up front that the engineering models that his company and other cellular carriers use to determine coverage maps aren't perfect, but says that T-Mobile's goal really is to improve accuracy by incorporating customer data into the matrix as well.

The problem with coverage maps is that they just don't tell the whole story.

It turns out that when you install the T-Mobile My Account app (opens in new tab) on your phone, you're given the option of sending diagnostic info (anonymously) to T-Mobile. Castle explains that the app occasionally collects signal strength measurements, which are then transferred to T-Mobile. The app also distinguishes what type of technology was used during that signal strength measurement (LTE versus Wi-Fi Calling, for example).

It's that data which T-Mobile is incorporating into the new maps. Anywhere you see a hexagon on the map is a confirmed data point derived directly from that sort of information.

Not every bit of customer-derived data is incorporated into the maps, according to Castle. T-Mobile waits until it has what Castle calls "a statistically valid number of samples" before incorporating it into the maps.

The problem with coverage maps is that they just don't tell the whole story. Just because an area may have 4G LTE coverage doesn't necessarily mean you can do anything with that coverage. I often see one, even two bars of 4G LTE on my iPhone 6 (connected to T-Mobile's network), but I'll still time out when instant messaging or trying to connect to the Internet.

Here's a practical example: I get one bar of 4G LTE coverage from the parking lot of my wife's work, also in the same town we live in. We often share a car, so I'll pick her up at the end of the day and try to let her know I'm there by texting or calling her. Her work, and the commute home, is in the dark magenta coverage area we see on this new T-Mobile map:

T-Mobile Map

If I can actually connect when I call, I'm amazed. If I can be understood, it's almost miraculous. Forget about actually using data. Just the other day she called me from the parking lot, and I couldn't understand a word she was saying. Yet she technically had a 4G LTE connection.

Here's another: Because in-house coverage for T-Mobile is so poor, and because Wi-Fi Calling by design prevents you from using some Handoff features like Call Relay, which I depend on, we don't use Wi-Fi Calling in my house. Instead, my family and I rely on a free T-Mobile-provided signal booster in order to use our phones in the house. Without it we're lucky to get one bar anywhere in the house.

T-Mobile still has significant technical challenges before it.

With the signal booster propped in an upstairs window, we get four or five bars continuously. So all the data we're reporting to T-Mobile show a strong, healthy 4G signal. Even though that's not reflective of what anyone off my property line is going to see, or indeed even what I see when I walk into my back yard or my driveway and try to make a call.

T-Mobile still has significant technical challenges before it. The company is trying to bolster rural coverage, and a particular weakness of T-Mobile, indoor coverage, by deploying cell transmitters that operate on a 700 MHz radio band. AT&T and Verizon both use 700 MHz and have much better indoor and outlying area coverage than T-Mo. That's taking time, and it's a patchwork effort because of problems with digital video broadcasts in some areas. What's more, not all phones T-Mobile sells or supports work with the 700 MHz LTE band it's deployed, including the iPhone 6 and iPhone 6 Plus.

From my perspective, I remain a T-Mobile customer for a few reasons: First and foremost, I pay a lot less for T-Mobile service than I did for AT&T, and get a lot more for the money.

Second, I genuinely like my interactions with T-Mobile support people: Their customer service and tech support folks really have gone above and beyond to help when I've needed it.

Third, despite my local connectivity woes, I've seen T-Mobile coverage improve dramatically in my area over the past two years. It's not perfect, by any stretch, but it is getting better.

And finally, I enjoy supporting the scrappy upstart: I like how disruptive T-Mobile has been to the competition, and I like being in their corner.

I just wish T-Mobile's marketing wouldn't get ahead of their engineering. Because no one likes being lied to. And based on what I read in the discussion thread on my last editorial and what I heard from you on social media, neither do you.

Am I off base? Is T-Mobile just doing what every other carrier does? Sound off in the comments and let me know what you think.

28 Comments
  • I recently got the S6 (I have an iPhone 6+ as well) .. I get 4G at my house on the iPhone .. I was stunned to see LTE w/ my S6 and be able to use it (16 Mbps down .. nothing to scream about).
  • Might be that your S6 supports the LTE Band 12 (700mhz) spectrum. The iPhone 6 and 6+ do not support this band. I sincerely hope Apple includes this band in the next iPhone. A handful of Android phones already do and the 700mhz spectrum is what everyone that is on T-Mobile wants access to.
  • That's correct - the S6 does support LTE Band 12 (the 700 MHz A Block that T-Mobile works with). If Almeuit is lucky enough to live in an area where T-Mobile is already broadcasting on LTE Band 12, they'll see much better indoor performance.
  • iPhones reception on T-mobile is pretty bad, one of the worst phones they have sadly when it comes to that. At my home iPhone will be toggling back and forth between LTE, 4G (HSPA), and even EDGE. My Lumia 925, my Samsung Galaxy Avant, and my Moto X all maintain LTE signal pretty much all day, with a very rare drop to HSPA
  • Good point on the signal booster station, it does give wrong info back to t-mobile.
  • I think this is something they can fix with a software patch.. they just need to send data indicating that signal is on a booster.. Generally, that info (what tower the phone is connected to) should be available, and they 'should' be able to identify it's actually from a booster local tower, not direct. They could even indicate on the map where boosters are being used.. Might give people an idea that while signal isn't great, many seems to get by with a booster.
  • Even if they can fix it with a patch, the gentleman I spoke to confirmed that they're not currently doing that, which puts the veracity of the info they're now publishing into question. Which is my point.
  • I dont think the number of customers that have the signal booster that also report their signal strength would even matter as far as the map is concerned. Just my opinion.
  • You've echoed my reasons for sticking with T-mobile to the dot. Especially their customer service. They are extremely pleasant to talk to and I always feel like they go out of their way to help(even more if you've been with them for a while). And when you get the electric recording on dialing 611, the first hit of 0 brings you directly to a t-mobile rep.
  • I wish every carrier could have up to date maps. I used to have tmobile but the service was so bad where I was most of the time and then of course the iPhone was only on ATT at the time I switched so never looked back. In my personal experience my interaction with ATT has been great. Just yesterday I posted a comment on their FaceBook page about how the last few days I have been getting slow speeds and received a response and someone trying to help. I did not think they would have seen that. I do agree that marketing and the engineers should be on the same page.
  • What no one seems ever to talk about is what happens in a power outage. I only have an anecdote: a few years ago we had a massive outage, and only Verizon's towers were supported by backup power. That's one reason we use Verizon rather than AT$T etc. I'm curious about other providers in this regard, but I've never seen it discussed.
  • All companies have backup power sources these days.
  • I just wish iPhone in general could get better reception, it doesn't seem to connect to LTE or stay on it as well as my other phones on T-mobile if it connects at all. If I go to a place with really low reception (pretty much only place around here like that is the hospital) I make sure to take one of my Android or Windows phones just in case.
  • That is one reason I have stayed with ATT. I get great speed and reception no matter where I am. I even had a signal inside the bottom of hoover dam. That was even 5 years ago.
  • "I just wish iPhone in general could get better reception..." My wife uses an iPhone 6 Plus and had continuous problems until we disabled Wi-Fi calling. Afterwards, it was like a whole new phone.
  • I don't have problems at all with actually getting reception where I live, the problem I have is staying on LTE, it's a little frustrating when the network I'm on randomly drops to HSPA or EDGE when I'm streaming.
  • I guess I'm confused as to why Peter is still on T-Mobile? A cheaper carrier that doesn't provide service when needed is far more overpriced than an expensive carrier that works when you need it. I'm on Verizon here in eastern Iowa because every alternative has subpar coverage, either here or when traveling.
  • He explained that in the end of the article. Sent from the iMore App
  • All I can say is that man you guys have shitty service overall down in the USA. The kind of things you describe in terms of poor quality and lost connections would be grounds for a law suit in Canada or Europe. I'm amazed that the service is that bad, and that no one seems to care about it much.
  • Look at the population density and amount of space in Europe compared to the US. The US has less people over a hell of a lot larger area.
  • Since the author has the iPhone 6, he has VoLTE support. I wonder if he has that enabled and is the cause for the poor voice quality at times...or doesn't have it enabled and has spotty GSM/Edge/UMTS coverage causing the poor quality/coverage.
  • I'm not surprised that they're basically BSing us to try to make their map seem more accurate than it really is. So I just ignore their map. What I really, really want T-Mobile to do is to fix their indoor signal penetration problem, or lack thereof. That band 12 can't come soon enough. I love my "unlimited everything" plan with T-Mobile and I get strong, super-fast LTE almost everywhere I go... as long as I'm outdoors. I just hate having no signal and getting "No Service" indoors. I lose all signal as soon as I enter most buildings. This is an even bigger problem when I'm at work. WiFi is simply not an option there due to their locked-down proprietary network. Having an iPhone 6 doesn't help either as it doesn't support T-Mo's new LTE band 12, but right now there simply aren't any other phones that do support it that I actually want (I don't want a locked, bloatware-infested carrier phone). My iPhone 6 is unlocked so there's nothing keeping me with T-Mobile and I can just walk anytime I want to, but if I'm going to keep my iPhone 6, I have to either stick with T-Mo and tough it out til September or whenever hoping that the next iPhone will support band 12, or maybe go back to AT&T, which I'd rather avoid. But then when I see how much cheaper my bill is per month, and how much faster T-Mo's LTE is in my area (when I'm outdoors), I'd really hate to give that up. So... I'm basically screwed, at least until T-Mo gets that band 12 going here and I can find a band 12-compatible phone that'll work for me.
  • So what is your solution? Most customers complain without offering any solutions. If you think you can do it better why don't you draw up a solution and discuss it with the person from T-Mobile? Sounds like you had the premier person from T-Mobile and just wasted his time complaining about how maps were wrong. Anyone can complain, but if you offer maybe 5-10 ideas for them to improve their marketing, maps, service, etc you might find yourself in a whole new arena. Maybe a job offer or something more can come of it. Just am getting kinda tired of hearing people complain only to complain. By the way Peter, I do love your columns and recently wrote an email to Rene about how iMore has improved my business and life. What a great site you guys created. Thanks for contributing.
  • While I know my reply is only addressing part of your concerns. When it comes to in-building cellular coverage energy efficient buildings are non-RF friendly. This is one of the primary reasons carriers are installing DAS (Distributed Antenna Systems) or "small cell". Also carriers are expecting 80% of data consumption to be consumed in-building which is why all carriers are investing so heavily to address this. Some more aggressive than others. Also understand on average it takes close to a year or more to build a new tower due to all the governmental red tape.
  • Sadly they appear to be doing what Canadian telecoms are doing. I wanted to report a deadzone when I got home. No word of lie. The rep asked me if I would mind driving and hour back north and calling from the spot. He had no answer when i asked them how I would do that from a deadzone. He suggested I borrow someone's phone from another provider.
  • Yep. So like the other carrier maps I've come across they simply are not accurate.
  • Been with T-Mobile for a very long time, currently my LTE signal is very strong, 5 bars all the time inside my house. Getting today from the SpeedTest app over 55mb down and 25mb up, inside my house. Outside my house it is even faster. Wasn't always like this, T-Mobile has improved coverage leaps and bounds in the last 12 months, they spend more money on updating towers then probably all other Carriers. It won't be very long before their LTE coverage will be as good or better than the other Carriers. My Iphone 6 and 5S has weaker radios or antenna than my Note 4, My area doesnt have Band 12 coverage yet so Im assuming it must be one or the other. Im getting 30mb down with my 5S, take the sim card out and put it in my Note 4 with an adapter and Im getting over 50mb down. I get 5 bars of signal strength on both phones but the Note 4 has much faster DL speeds. Hey, 30mb isn't anything to complain about but just making my point how radio strength or antenns can be an issue with some devices. My iPhone 6 gets the same speeds as the 5S, I ordered my SGS6 with 128gb of int storage, have not received it yet. I'm assuming it will have the same radio strength as my Note 4, it better. One other point, my Ipad mini with retina display, 128gb of int storage gets at least 10mb faster DL speeds than both my iPhones. Not sure if the radios are the same in the iphones and the ipad mini, maybe it is the antennas??? Just something to think about. After all that rambling I have to say I have been with all the major Carriers and never had better coverage or plans than I do with T-Mobile. Thank You T-Mobile, Thank You John Legere.
  • I just switched from VW to TM. VW had great coverage (though pricey), but couldn't provide a signal at my house (where i work). TM sold me on their recent "upgrades and expansion of their LTE service. BS is right. i'm switching back today - day 26. I simply cannot maintain a call with TM. Continuous dropped calls. If i'm not on WiFi i sometimes cant make a call at all, and if i am on WiFi, i get dropped calls because the phone tried to switch to a transient WiFi signal. Also, same as you, no signal at home without a signal booster. The problem with the booster becomes not being able to move around the house because the signal wants to jump from our booster to the tower and we again lose the call. Frustrating to say the least. The savings are simply not worth the frustration and i cannot conduct business like this.