Category Archives: T-Mobile

Texting May Work When Everything Else Fails

Our recent experience with hurricane Irma confirms the wisdom of not putting all of your communication eggs in one basket. The storm interrupted communications for hours and days. Immediately afterward, my phone had a good wireless RF connection to T-Mobile’s cell site, but no IP (Internet Protocol) connection. Text messaging using SMS (Short Message Service) worked fine. (SMS is a telephone — not Internet — protocol. It uses the telephone industry’s venerable Signaling System 7 to transport its messages.)

On the other hand, messaging apps such as WhatsApp, Facebook Messenger, and SnapChat rely upon IP to transport their messages. Without an IP connection, these messaging apps wouldn’t have worked. The plain Jane texting program that’s built into my Android 5 phone doesn’t need IP. SMS originally used GSM for message transport. Now it also uses LTE, CDMA, etc.

T-Mobile provided SMS and voice calling service for days after the storm, before they restored my IP connectivity. They said that about 700 cell sites in Dade and Broward counties had been degraded by hurricane Irma. 

Caveat: SMS isn’t secure, as its transport mechanism, Signaling System 7, lacks an authentication protocol. 

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New Samsung SM-G360T phone

My trusty Samsung SGH-T399 phone began to flake out last week. First it insisted that a number of apps needed to be reinstalled, then some apps lost their data. These sound like memory failures. Within a few days, the phone refused to re-start.

samsung galaxy core prime
Samsung SM-G360T

I replaced it with a low-cost Samsung SM-G360T, for $140 from the local T-mobile store. T-mobile calls it a GALAXY CORE Prime™. It’s small (4.5 inch screen), includes LTE, a quad core CPU, 8 GB of memory, 5 megapixel camera, replaceable battery, and a slot for a micro SD card up to 200GB. To keep costs low, Samsung seems to have deleted the magnetic sensor, the automatic screen illumination control, and lighted “back” buttons. I can live without these niceties.

The phone includes Android 5.1.1, which in most respects is an improvement over my old SGH-T399’s Android 4.

I notice on T-Mobile’s website that they’re now discounting this phone for $99. I recommend it, if your needs are similar to mine.  At that price, I may buy a second SM-G360T, as a backup phone.

T-mobile updated my SGH-T399 phone

(Originally published December 9, 2015) Last week,  without warning,  my Samsung SGH-T399 Galaxy Light phone from T-mobile began to download and update its system software to version T399UVUAOH2. Stagefright Detector now reports that my phone is no longer vulnerable to the Stagefright virus.

My phone’s About screen reports that its Android operating system remains at version 4.2.2 (Jelly Bean), but its kernel is now dated August 25, 2015 (Korean standard time).

t-mobile stagefright 480w

  • Tip: If your Android phone is vulnerable to the Stagefright virus, you can reduce (but not eliminate) its vulnerability by, within the Messaging app, turning off the Auto retrieve setting. The Stagefright virus arrives within an SMS (short message service) multimedia message, so if your phone is vulnerable, you do not want to download these messages.

Update, February 27, 2016: T-Mobile again updated my T-399 phone. It still reports Android version 4.2.2, but now reports baseband version T399UVUAPA1 and is dated January 4th, 2016, 20:32, Korean Standard Time. According to T-Mobile’s note that accompanied the update, it improves voice over LTE (VoLTE) and unspecified security features.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

 

 

T-Mobile’s “Binge On”

With the recent introduction of its Binge On service, T-Mobile US is again mangling the English language. Binge On provides preferential treatment of packets  “from Netflix and Hulu (which are T-Mobile partners) but not YouTube (which isn’t) without having those streams count against their data plans.” (Wired article, T-Mobile Confirms It Slows Connections to Video Sites, 7 Jan 2016).  Dig a little deeper and you’ll discover that if you have the Binge On “service”, T-Mobile will throttle data from YouTube et al to 1.5 Mbps. Some “service”!

Surprise: Binge On is switched on by default

If, like me, you have a legacy “Simple Choice Plan: Unlimited Talk + Text”, you may be surprised to learn that by default your account now includes the Binge On “service”. (Thank you T-Mobile, I prefer that you not throttle my YouTube videos.)  As far as I can see, Binge On provides no advantage for users with truly unlimited data plans. In fact, it slows down their YouTube viewing. Here’s how to turn Binge On off:

  • Log in to your T-Mobile account
  • Click on Profile (upper right hand corner)
  • Click on Media Settings
  • Click on Binge On to turn it off (as illustrated below):

t-mobile binge on 1184w

I mistakenly thought that T-Mobile’s legacy plans were immune from encroachment by throttling. I was wrong. Apparently the FCC wishes to chat with T-Mobile about its latest twisting of words’ meanings: T-Mobile’s Binge On: When throttling may not break the rules, Arstechnica, 7 January 2016.

Is Binge On legal?  According to the EFF,

. . . throttling all traffic based on application type definitely violates the principles of net neutrality. It also obviously violates the FCC’s Open Internet Order, which says that ISPs

“…shall not impair or degrade lawful Internet traffic on the basis of Internet content, application, or service…subject to reasonable network management”

Cel-Fi LTE signal booster

T-mobile works fine for me, except in my house. I think that the nearest T-mobile cell site is about a half-mile away, but the signal path is filled with old growth (signal absorbent) trees. I can’t use my cell phone on the ground floor, and it’s usable in only a few spots on the second floor.

Neither T-mobile’s tech support people nor its store personnel have helped. I read that T-mobile is now providing “signal boosters” to customers with weak signals in their homes. Apparently AT&T and other carriers offer similar systems.

CelFi LTE booster from T-mobileOn Friday, I fetched a new T-mobile “Personal CellSpot 4G LTE Signal Booster” from the T-mobile store, after paying a $25 deposit.

My booster is the “Cel-Fi” model RS3 or DUO, manufactured by San Diego-based Nextivity. It consists of two small boxes — the window unit and the coverage unit — and their wall wart power supplies. The window unit receives T-mobile’s LTE or HSPA signal (presumably at 1700 MHz), demodulates it, and transports the data via a 5 GHz unlicensed UNI link to the coverage unit. I placed the window unit on the second floor and the coverage unit on the ground floor.

cel-fi system schematic in house

What is its theory of operation?

Apparently the system is essentially a repeater. I have no idea how completely it demodulates the tower’s signal before creating the in-house signal. Is the in-house signal that’s transmitted by the coverage unit on the same frequency as the tower’s signal that’s received by the window unit? I don’t know, but I doubt it. Nextivity merely states that the coverage unit “cleans up” (whatever that means) the signal. Neither unit has any user interface other than some front panel LEDs.

Does it work?

Placement of both units is critical. I needed about an hour to get the system working throughout my house. Without field strength measurement instruments, I relied upon the limited information that’s provided by the units’ front panel LEDs. It works.

I’ve found almost no technical information about this system except a bit in a thread on Howardforums and a press release regarding Nextivity’s use of 1/4 and 1/2 Watt output power amplifiers in this product. If you have technical information — especially antenna radiation patterns — on this product, please let us know.

What if it quits working?

Occasionally (maybe once a week) the received signal from the Coverage Unit drops to one bar and/or my phone reverts to a slow EDGE connection. I’ve found that resetting the Cel-Fi system restores signal strength and LTE speeds at my phone. Follow these steps, in sequence:

  1. Remove power to the Coverage Unit
  2. Remove power to the Window Unit
  3. Wait 30 seconds
  4. Restore power to the Window Unit
  5. Restore power to the Coverage Unit
  6. Wait a few minutes while the two units establish a good wireless link and the Coverage Unit adjusts its output level

You should eventually see a full 5 bars received signal strength at the phone.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

Restore Android contacts

I drowned my three month old Samsung SGH-T399 Galaxy Light phone. It slipped into my bath water as I was using it in the tub. I quickly rescued it, yanked out its battery, SIM card, and SD card, and tucked it into a nice dry bed of uncooked white rice for the night. In the morning it started normally, but its display flickered and failed after warming up.

Import contacts.vcf screenshotI purchased a replacement SGH-T399 phone and installed my favorite apps on it. My Google Mail contacts were restored,  but the remaining contacts were not restored. By moving quickly,  I was able to go to the Contacts app on the old phone and export them to a contacts.vcf file. Then I used a USB cable to make the old phone a slave to a Windows 7 PC host. I copied the contacts.vcf file to the host PC’s store. (The contacts.vcf file is located in the phone’s /storage/emulated/0/ folder.)

Then I removed the old phone from the USB cable, and replaced it with the new phone. Next I copied the contacts.vcf file from the PC’s store to the /storage/emulated/0/ folder on the new phone,  ran its Contacts app, and imported contacts.vcf. Done!

My new phone now has the contacts from my old phone. Both phones run Android 4.2.2.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

Liberate storage on Samsung SGH-T399 phone

I discovered a method of freeing storage space on my Samsung SGH-T399 Android phone. Podcasts had stopped streaming, probably because the phone had run out of free storage space for caching. How could I create free storage space? I learned that the hidden /mnt/sdcard/.face folder had grown to 2.65 gigabytes and contained 67,000 files(!). I gambled that the facial recognition files contained there were nonessential.

I deleted the /mnt/sdcard/.face folder, then created a new empty /mnt/sdcard/.face folder. Suddenly the phone had 2.65 GB of free storage. Yesssss!

I used a terrific Android app, ES File Explorer, to discover this bloated folder, delete it, and create a new empty one. Its SD Card Analyst tool displays folders sorted in descending order by size. The .face folder was at the top of the list.

Note that the folder named sdcard isn’t actually the physical sdcard. For some reason, Samsung’s Android file system calls this phone’s internal storage folder /mnt/sdcard. The physical sdcard is named /mnt/extSdCard.

screenshot by xda-developers

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

T-Mobile pulled the plug on their contacts backup server

Here’s evidence that some communications companies do a poor job of communicating not only with their customers, but internally, as well.

t-mobile contacts backup screenLast Friday, my trusty old Samsung SGH-T679 Android (Gingerbread) smartphone died. I purchased a replacement SGH-T399 from the T-Mobile store, and the salesperson wrote my subscriber data to its micro-SIM card. I merely needed to install my favorite apps and restore my contacts from T-Mobile’s contacts synchronization server:

  1. Install apps? Check.
  2. Restore contacts? Negative. Why? In July, T-Mobile pulled the plug on their contacts synchronization server. It, and my contacts list, has been taken off-line.

After a little hunting, I found this message on T-Mobile’s website:

Contacts was a free service that allowed you to backup up to 5,000 contacts on a secure T-Mobile server. Contacts has now been retired.

If you stored contacts on your phone, don’t worry, they are still there and will remain on your phone. But what happens if you lose your phone and haven’t backed up your contacts? Without a backup, your contacts will be lost forever . . .

I tested the T-Mobile contacts backup (or synchronization) system last year. It worked fine. When I needed it last week, it didn’t work. I cannot imagine a reason why T-Mobile would think that closing down the contacts backup service was a good idea.

Rachel, T-Mobile’s helpful second-level support person, reported that T-Mobile’s management told employees that third party email providers such as Google provide contacts backup services, gratis. The problem is that Google’s terms of service grant Google carte blanche to your contacts (and everything else that you store with Google). They’re free to reveal all your contacts to anyone, including your competitors.

  • An incomplete restoration
    Rachel had a subset of my contacts in the form of a comma-delimited file (.CSV) sent to me. It was very out of date — maybe a year old — and contained first name, last name, and phone number only. Email address, notes, company, etc. were missing. I imported this file into a spreadsheet, edited it, and imported the edited CSV file into my contacts.

I’m surprised that Rachel and her colleagues at T-mobile didn’t object when management proposed this dumb idea. Customers seem not to have been asked their opinions. It sounds like at T-Mobile, all communication is one way: from the top down.

This dumb move by T-mobile has annoyed other customers. My guess is that it’s a breach of my contract with them.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

OpenSignal app for Android

About a year ago, I wrote an article about my attempts to locate T-mobile’s nearby cell sites. I’m still having difficulty.image I’ve tried several Android apps that measure signal field strength, with varying success. I’ve had the best results with OpenSignal 2.0 (available free from the Android Play Store). This YouTube video is a good introduction to the app.

OpenSignal seems to do a good job of measuring signal strength and data transmission speed. However, its estimates of cell sites’ locations aren’t at all accurate. I think that it relies upon its own database of cell sites’ geographical coordinates — and these data are inaccurate. It’s frustrating, because everything else about OpenSignal works nicely.

Most of OpenSignal’s many features work well. It has the polished feel of a good commercial app. I gather that OpenSignal regularly updates their cell sites location database, so there’s hope. In the meantime, I give it four out of five stars.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

I nearly melted down my phone

While listening to a podcast on my Samsung mobile phone via the Tunein app, a pop-up announced, “Charging paused. Battery temperature too low or too high.” The pop-up remained on screen until I unplugged the charger. The battery had only about a 6% charge, so as soon as I unplugged the charger, another pop-up warned that the battery needed to be charged. Catch 22. Room temperature was probably about 77 degrees Fahrenheit.

imageI grabbed a cold pack from the freezer and rested the phone on its icy carcass. The over-temperature warnings ceased while I simultaneously listened to the podcast and charged the phone’s battery.

Decades ago, I helped develop military radio communication hardware. The products needed to pass environmental tests for vibration, shock, high and low ambient temperatures, and humidity — while under continuous full-load conditions. We invested many hours in heat management.

My mobile phone is clearly incapable of passing such tests. It’s intended for intermittent use — what’s known as low duty cycle usage. I’d guess that my phone can handle about a 10 to 15 percent duty cycle at full output.

This is probably as good as we can expect from consumer-grade products. We just need to have frigid cold packs ready if we want more.

My phone: Samsung SGH-T679. T-Mobile Insight II 4G.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

A quick fix for Android net connect problems

Airplane Mode screenshotOccasionally my Samsung Insight II phone (SGH-T679 running Android Gingerbread 2.3.6) quits communicating via IP with Internet hosts. Often, a wireless connection to a T-Mobile tower exists but there’s just no IP communication. Also, occasionally my phone insists that it can only establish a (low speed, perhaps 50 kbps) EDGE wireless connection to the tower; it refuses to connect at higher speeds (such as UMTS, HSDPA, or LTE).

A simple fix — short of shutting down and restarting the phone or system troubleshooting — is to temporarily place the phone in Airplane Mode (which shuts down its wireless radio transceivers) and then turn off its Airplane Mode (which starts its wireless radio transceivers). Your phone should connect to the cell site with the strongest signal — which may be different than the site that it was connected to before. Nine times out of ten this works for me.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

Samsung SGH-T679 not charging

Occasionally, for no apparent reason, my Android phone refuses to accept a battery charge. (originally published 15 February 2014)

Samsung Exhibit II SGH-T679 phoneHere’s the only way I’ve found to fix this problem on my Samsung Insight II SGH-T679 with Android 2.3.6 Gingerbread phone:

  1. Remove charger
  2. Turn off phone
  3. Remove battery
  4. Remove SIM card
  5. Remove SD card
  6. Wait at least 3 minutes. (I’ve had to wait as long as 60 minutes.)
  7. Replace SD card
  8. Replace SIM card
  9. Replace battery
  10. Turn on phone
  11. Plug in charger

This reset procedure works for me. It may or may not work for you. (8 Oct 2014) It also works for my new SGH-T399 phone.


Update

7 August 2014Samsung charger This may or may not be a coincidence, but I’ve found that since abandoning third-party battery chargers and returning to a Samsung manufactured charger, my phone’s battery behaves better, without loss of charging function.

I’ve also stopped buying third-party batteries. They’ve been short-lived. I found what seems to be a genuine Samsung battery on Amazon. The combination of genuine Samsung battery and Samsung battery charger seems to provide both longer battery discharge times and better charging behavior.

I’ve not needed to resort to the charging system reset procedure since installing the genuine Samsung battery and using the genuine Samsung charger.

Extra credit article: How to prolong lithium based batteries

Also see: Repair and prevent battery charging problems on GSM phones.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

CTIA’s stolen cellphone blacklist

A stolen smartphone can fetch $200 to $300, so smartphone theft remains a problem. CTIA’s website includes tips on how to deter smartphone thefts.

CTIA logoThe CTIA (Cellular Telecommunications Industry Association) announced in November that it had integrated its stolen cellphone database with similar international databases. A recent Verge article describes the importance of the overseas stolen cellphone market and the controversy that surrounds a built-in “kill switch” for smartphones.

The CTIA insists that its new improved cellphone blacklist will make “kill switches” unnecessary. We’ll see what happens to the market value of stolen phones.

FCC’s Mobile Speed Test

The FCC has released a test version of a cellular data transfer speed measurement app for Android devices. It’s available from https://play.google.com/store/apps/details?id=com.samknows.fcc.

fcc-test-resultsThe FCC has published the Android app’s open source code on its Github site. They’ve promised an iPhone version. It’s being developed by Samknows.com.

According to the app’s FAQ, “the application will run continuously in the background, periodically performing measurements.” I’m not enthused about having this app running continuously. I’ll probably uninstall it after each measurement run.

A feature of this app that I like is that it collects and reports “cell tower ID” and “cell tower location code” — data that may help my quest to pinpoint the physical location of T-Mobile’s nearest cell site. It also reports received signal strength in dBm.

The speed test data are collected from your mobile device and aggregated by the FCC. Let’s hope that they use the data to hold the carriers’ feet to the fire.

One reported problem is that the app, when testing over a WiFi connection, thinks that it’s connected via LTE. Also, it may have contributed to problems I had with other apps today.

4G??

If you examine the screenshot, you’ll see that although T-Mobile claims that the wireless connection (which was HSDPA when I snapped the screenshot) is “4G”, the download speed is a wimpy 1 Megabit per second. This disproves T-Mobile’s claim that HSDPA+ is “4G”. (The ITU specifies that 4G system mobile phones have a minimum peak download speed of 100 Mbps.) Maybe the FCC or FTC will do their jobs and slap T-Mobile for false advertising.

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695

Tech support

Today my T-Mobile Android phone suddenly stopped communicating with the Internet. I quickly ran through the usual troubleshooting steps. One step is to check IP connectivity by pinging an IP address on the Internet. I had no IP connectivity, but did have a decent RF HSDPA connection to a nearby cell site. These results suggested that T-Mobile’s backhaul link to their local cell site was broken.

android-pingI phoned T-Mobile customer hinderance assistance. Then I went through two tech support people who had no knowledge of the IP ping command. I asked to be transferred to someone who was familiar with ping. That person introduced herself as a member of T-Mobile’s highest tech support level. She didn’t know the ping command either but told me that she had been through the T-Mobile tech support training. She told me that that was six years ago.

This is normal. Tech support people who don’t understand the vocabulary of their trade is the rule — not the exception.

If you held a tech support position, wouldn’t you want to learn as much as possible about the technology? Why doesn’t T-Mobile require that its tech support staff know basic network vocabulary?

Visit my website: http://russbellew.com
© Russ Bellew · Fort Lauderdale, Florida, USA · phone 954 873-4695