Unlocked Galaxy S6 text & data work but no phone calls don't.


    Around the June 2th I decided to switch from AT&T to T-Mobile due to them charging me 500 dollars for some changes to my plan that I wasn't made aware of. I had service with them for around 10 years now but decided to give T-Mobile a try. I saw the new Switch-To-T-Mobile offer and decided to go for it as September last year I got 2 new Galaxy S6, one for me and one for my wife; when I switched I had purchased a temporary phone so I could work (I need a phone to do my job) and wait for the money to pay for the other 2 phone would come. Around 10 days ago I got the money and was able to pay for both phones and get them unlocked and everything was fine from then on.

    Here is where the problem comes in:

    Around 3 days ago both phones started to have problems, messages wouldn't send, calls would drop and terrible reception. My wife had told me that she was having problems but I told were not to worry about it and that it was just something temporary.
    Then 1 day passes and the problem get worse, now we are not able to make calls (Sometimes we are able to but we have to wait around 2-3 minutes for the call to come out and it would be really choppy and noisy) or receive any calls (This one seems to be more permanent and never works.
    The strange part come in the fact that we are able to use the data (4G LTE at all times) and send/receive messages.



    TLDR: (For those who don't feel like read my long wall of text):

    1) I got 2 phones from AT&T (Both Galaxy S6 and unlocked)
    2) Both phones were switched over to T-Mobile and worked fine for about a week.
    3) Around 3 days ago I lost all ability to make or receive calls from both phones
    4) The data & messages for both phones seems to be just fine but the ability to create/receive calls just isn't there.


    Here is what I have tried:
    1) I tried changing the APN to T-Mobile's APN (It was already there but I added a new one with T-Mobile's specification).
    2) I tried restarting the phone (A few hundred times).
    3) I tried switching the SIM Card to the temporary phone that I bought from T-Mobile and that seems to work fine.

    4) I have tried using an app called "4G Switcher" to Change the netowork type to one compatible with T-Mobiles.
    5) I tried disabling and enabling Air-Plane mode.
    6) I tried Swapping SIM Cards from a working T-Mobile phone to this one.

    7) I tried disabling/Enabling 4G LTE, 2G and 3G  and none seems to work (Apart from internet data like I said before)/
    7) I tried contacting T-Mobile support.

    All of the above have yielded no results.


    Additional Information:
    1) My sons AT&T Galaxy S5 which he used for about 2 weeks with T-Mobile and then turned off and never used again when I got him an S8 From T-Mobile itself no longer works (There was no change anything could have changed with the settings of this phone due to it being off the whole time)
    2) When I make a call from any of the phones (Apart from the one that due work) the signal drops from 4G LTE to Edge and then to no signal (If I am lucky it will stay on Edged for long enough for the call to go through))
    3) I am also able to receive voice mails from any and all phones.


    Some threads on this site with similar problems (Different in the way that they can make calls but have no data and I have data & text messages but can't make calls)

    Samsung S7 Edge At&t To T-Mobile. Can't get 4G or any internet. Text & calls work
    Unlocked AT&T S7 Active - moved to T-Mobile: Not working well.

    Here are the APN settings that I have reapplied to both phones:
    Network, APN, and VoLTE: Samsung Galaxy S 6


    If anyone has ever encountered or heard of this issue please let me know, I am desperate.

      All replies

      • drnewcomb2

        I'm having some trouble sorting out the sequence of events but I wonder if the phones are compatible with T-Mobile's VoLTE? Incompatible VoLTE would result in having phone calls drop down to 2G or 3G. If T-Mobile refarmed some of their spectrum in your locale, it might have made it difficult for the phone to fall back to 2G or 3G. Just a guess. Where are you located?

        • drnewcomb2

          Yours is not the first recent complaint from NYC about changes that have reduced signal availability. What seems to have happened is that T-Mobile moved their 3.5G (HSPA+/UMTS) signal to the AWS band (band-4) and converted some of the PCS band to LTE. The Galaxy S6 does not have UMTS band-4 and the AT&T version (G920A) may not have compatible VOLTE. This could make you dependent on a strained 2G network for voice. This is just a theory but it's consistent with some other recent complaints from the NYC market. Your best solution may be to get a couple new phones. I'm suggesting the Moto G5 Plus, as it's compatible with all major carriers, so you can take it with you if you decide to go elsewhere. The Moto E4 is also a good choice.

          • carlossanunga

            I have also tried factory resetting the phones and no luck.

            • carlossanunga

              So basically, I am screwed. Fantastic, the best part is that I just switched from AT&T because of service problems and now I am in the same situation and now with the "need" of 2 new phones.

                • drnewcomb2

                  One of the hazards of Samsung phones (which few people understand) is that, unlike iPhones, they are highly tweaked for the carriers that sell them. There is some compatibility with other GSM/LTE carriers but it can be 2nd rate. There are a few phones on the market that come unlocked and are capable of working with any US carrier. I mentioned some of the Motorolas, there are also Nexus & Pixel phones and some of the iPhones maybe a few others. Your Galaxy S6 would probably work fine in just about any market except NYC and maybe Denver.

                  • drnewcomb2

                    Something came to me. You might have VoLTE turned off: Check the following:

                    Samsung Galaxy Note & Galaxy S series

                    Tap Phone > Keypad tab.

                    Tap More options > Settings.

                    Tap Call > Voice over LTE settings.

                    Tap Use VoLTE when available or Do not use VoLTE.

                  • carlossanunga

                    Alright, so I have contacted T-Mobile once again and spoke to a very nice lady who told me that this changes that they have made around the New York areas where I live shouldn't have impacted my service in the way that it did. She has field another ticket with even more information to see if there is anything else that they have overlooked.



                    I also followed what drnewcomb2 told me to do and that option is not there on my phone but something I did try was downloading an App called "4G switcher" and changing the phone to GSM Only. While on that mode I only get "EDGE" type reception but I am able to receive phone calls and sometimes even make them but the reception is very poor and there is no data.


                    At this point I am starting to think that there is some kind of problem on your guy's side since my neighbor who also has T-Mobile is having the same problem and he has a T-Mobile Galaxy S7.

                    • tmo_chris

                      Hey carlossanunga


                      Just checking in here to see how things are going? Have you heard anything back on the last ticket that was filed?

                        • th_wired

                          So, I have been a tmobile customer for 8 /9 years. And asked my friend to move to tmobile, in good faith. She took her unlocked att samsung s6 to tmobile store and they moved her over. Never checked the compatibility of the device and told her it might take 24 hours for the service to kick in. Fast forward 2.5 weeks. She still cant get a call.. 7/8 different chats, calls to tmobile corporate and store and network reset, phone reset , high level tech support, create a ticket for engineers and all that jazz, and no phone calls are getting through.

                          And now, they came down to conclusion, my friend needs to buy a new phone.

                          This really is tmobile's fault that the network-device is not compatible and the rep did not check the phone compatibility before moving her over.

                          And when we asked , what can tmobile do to offset buying a new phone...

                          guess what the response was...


                          We can offer you one time 20 DOLLAR CREDIT.


                          oh my.. amazing .. a whole 20 dollars...


                          The most amazing customer service.. We got so annoyed , we just ended the chat. Tmobile can keep that 20 dollars, and we are canceling our 3 lines.

                          Jesus.. this is  the worst customer service experience, spanning 7/8 reps and a tmobile store. Is this how, tmobile wants to be the uncarrier.. by basically not carrying our calls through their network and pushing the customer to buy a new phone, when the move was done a store. What good are these store employees?

                            • dragon1562

                              So just to be clear, BYOD for all carriers fall with the customer to find out if they are compatible. The simple reason is that there are to many variants of phones and to many phones in general to check. T-mobile has been making constant upgrades on its network to handle all the trafic and as such sacrifices are made. I have the S8 and have seen nothing but benefits by keeping a fairly recent device. Prior to the GS8 I used a Nexus 6p which is a unlocked device that also worked perfectly as well as iphones. Point that I'm trying to make is that if you upgrade your device, you will likely enjoy a even better network than before.

                          • ifittakesallnight

                            I've had Tmobile for years, and I've been using an unlocked Galaxy S6 Edge for the last 2 years without problem. Suddenly this summer, I started experiencing similar problems. Incoming calls started getting sent straight to voicemail. Outgoing calls take a long time (tens of seconds) to connect and are often bad quality. Data was however fine. I upgraded Android from 6 to 7, but this did not help. Forcing the phone to use only 3G/2G fixes the problem at the price of losing LTE. I spoke with an online Tmobile rep who suggested I try getting a new SIM. When I arrived at the store (Manhattan), the Tmobile rep immediately recognized the problem and said that Tmobile's upgrade of the network was causing problems with unlocked phones. He recommended switching to a newer unlocked phone or one of theirs (old or new). I'm more inclined to switch carriers at this point.

                            • throwaway100

                              Hi all,


                              I am having the exact same problem, I'm from Brooklyn, New York. I bought an unlocked Samsung S6 G920A. I cannot receive any or make any calls from it. I went to a T-Mobile store and the rep told me there would be no way I will be able to get the phone to work. (Rep also confirmed the phone is unlocked) What is going on?

                                • drnewcomb2

                                  It's a compatibility issue. T-Mobile repurposed their 1900 MHz spectrum in NYC from UMTS (a.k.a. "4G", WCDMA) to LTE. They may have left some UMTS running in the AWS band, which this phone does not have. GSM is now a very thin service running in the guard-bands of the 1900 MHz LTE signal. Now, the G920A does have LTE bands 2, 4 & 12, which T-Mobile uses but it may not have compatible VoLTE firmware to handle voice and text over LTE. One thing you should check is if VoLTE is turned on or off. I believe that the default on an AT&T device is VoLTE turned off.  You might be able to solve the problem with this phone by reflashing it with T-Mobile's firmware but that's beyond my experience level.

                                  1 of 1 people found this helpful
                                • pjneveshiller7

                                  I have used a non-carrier unlocked Galaxy 6 for nearly  2 years with no problem.  Last week we updated to the unlimited family plan.  At about the same time, I began experiencing the same problem -  text and data but no phone while at home. It seems to work fine when I leave the house. I called Support and after an hour  he suggested new SIM card. My husband went to the T-Mobile store  and they suggested that my phone was old technology and that I would be better off with a T-Mobile phone. Oh and the phone worked there But not once back home.  On his second visit they told him that they were working on towers in our area. Also suggested a boost for home.  I went to another T-Mobile store where they tried a new Sim card and phone stopped working once I got home.


                                  When it was suggested that we switch the unlimited family plan 4g there was no discussion or warning that my galaxy s6 might be problematic. Everyone's been wonderful but I'm starting to regret T-Mobile technology especially when you say you can bring your unlocked phone.  My husband and daughters iPhones are T-Mobile and working fine.  My galaxyhas been fine at home and everywhere for 2 years...is it the conversion to LTe suddenly causing this? Or it t-mobile updates to their towers and would a booster help?

                                    • drnewcomb2

                                      pjneveshiller7 wrote:


                                      ...is it the conversion to LTe suddenly causing this?....


                                      Pretty much, yes. It's the fact that your phones relied on UMTS band-2 (1900) and GSM for voice calls. When band-2 is converted to LTE and UMTS is moved to band-4 (1700, AWS) your phone can't follow it. Most models of the S6 didn't have UMTS band-4 but T-Mobile's did. I agree that T-Mobile has not handled this situation in the best way.

                                    • icefyre

                                      Same exact issues with unlocked AT&T S5 also in the NYC area. Worked great for a year and all of a sudden stops making and receiving phone calls.

                                      If you type *#2263# you can select your frequency bands on an S5. If you use just GSM voice calls work great but data becomes slower than a 1990 dial-up modem (0.03 download!) if you switch to LTE then data works great but can't make or receive phone calls. T-Mobile definitely did something in the NYC area. When I went up to the Pocono mountains all of a sudden my phone started working again so it is definitely the network.

                                      • parvezin

                                        I am having similar experience here in NJ/NYC as well for past few weeks on my unlocked S6 Egde (SM-G925F)


                                        I think T-Mobile should no longer brand itself "UNCARRIER". They say they are reframing their frequencies to improve their network for next generation but what about existing devices on their network. My S6 Egde (SM-G925F) that was working flawlessly just a few weeks ago is now useless. I no longer get their 3G (HSPA & HSPA+) signal, very spotty 2G and LTE signals and none of my voice call - incoming or outgoing completes .


                                        So basically if you have a non Magenta branded phone you are on you own. I see T-Mobile figured a smart way to force subscribers to get them buy their carrier locked "Magenta" branded phones and lock them into 2 years EIP contracts.

                                        • jsimmons00

                                          I am having the same issue . Depending where i am will determine   will determine if i can make and receive calls. This is not an unlock issue this is tmobile changing their towers and we get screwed. They need to pay for the new phones.