Develop Bugs

[Q] Strange service issue with unlocked S3 on T-Mobile

Greetings everyone! I'm a long-time lurker on this site, but have a bizarre problem that I need help with. I've searched all over, and haven't found anyone with this issue. Hopefully someone here can help! Ok, here it goes.
I purchased a used AT&T Galaxy S3, unlocked it, and put it on a T-Mobile prepaid plan. Everything works properly (calls, texts, data, etc.). But when I get to work I have the problem. While I'm in my building, the phone will show full bars for service, but it tells me it's not connected to any network when I try to do anything. If I try to make a call, it says for emergency calls only. Basically it acts the same as if the bill hadn't been paid, so they suspend your service while the phone still shows a signal. As soon as I leave the building, everything comes back as normal.
At first I was thinking the building was a dead zone, but it doesn't add up. Everyone else at work is always on their cell phones walking all around, and I've asked around to see if anyone else had these problems. Everyone says they have no reception issues at all, coming from people on various networks. Also, if it were a dead zone, I wouldn't think it'd be showing fluctuating signal bars. So I'm stumped, and desperately need to figure this out. Any ideas?

Tried a different modem?
Sent from my SAMSUNG-SGH-I747 using xda app-developers app

lonz358 said:
Tried a different modem?
Sent from my SAMSUNG-SGH-I747 using xda app-developers app
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I tried three different modems this morning. No luck. Anyone have any other ideas?

damdlux said:
I tried three different modems this morning. No luck. Anyone have any other ideas?
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Flash a T-mobile ROM ? Since it's unlocked why not flash a stock or close to stock T-mobile ROM. A conflict of some sorts there

hednik said:
Flash a T-mobile ROM ? Since it's unlocked why not flash a stock or close to stock T-mobile ROM. A conflict of some sorts there
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Would I be able to get a stock T-mobile rom without having to downgrade from 4.1? The only one I could find was for 4.0.4.

damdlux said:
Would I be able to get a stock T-mobile rom without having to downgrade from 4.1? The only one I could find was for 4.0.4.
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http://forum.xda-developers.com/showthread.php?t=1949687
UVDLJA I believe it is is the t mobile stock one with root injected you can flash with odin
Sent from my SAMSUNG-SGH-I747 using xda app-developers app

Ok, so an update on this situation. I flashed the T-Mobile stock firmware via Odin as suggested. I tried that with a combination of different modems, and nothing worked. I finally caved and bought a T-Mobile S3 T999, which arrived last night. On my way to work I had 4G just about the whole way, seemingly great service. As soon as I got inside, the problem was back. Five bars, no service (now saying not registered on network). I'm starting to wonder if it's the fault of the S3 in general having poor signal quality, or if it's T-Mobile service. I'm hoping maybe someone else has some new ideas to try out, or suggestions on if I should get a different phone or network.

damdlux said:
Ok, so an update on this situation. I flashed the T-Mobile stock firmware via Odin as suggested. I tried that with a combination of different modems, and nothing worked. I finally caved and bought a T-Mobile S3 T999, which arrived last night. On my way to work I had 4G just about the whole way, seemingly great service. As soon as I got inside, the problem was back. Five bars, no service (now saying not registered on network). I'm starting to wonder if it's the fault of the S3 in general having poor signal quality, or if it's T-Mobile service. I'm hoping maybe someone else has some new ideas to try out, or suggestions on if I should get a different phone or network.
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Try this: http://forum.xda-developers.com/showpost.php?p=36801042&postcount=4
Dunno if it's gonna work but can't hurt to try.

[Q] Signal issues i747 on T-mobile. Any help or suggestions appreciated!

I have an unlocked AT&T i747 on T-mobile's $30 100 min unlimited text, and 5GB 4G data plan.
It is running a fitsnugly nightly build of CM 10.1 for d2att
Was previously running Leankernel and now i'm running Ktoonsez's kernel
I unlocked using this method.
The Issue: My signal switches between H+, 3G, E, and rarely G. All while being in the same spot. It spends 90% of the time on E.
This happens in areas of great reception, indoors and out.
Rarely will H+ happen and 3G is very sporadic too.
I live in the heart of a major city (Boston) where T-mobile is prepping LTE so I can get their 3G/4G on the refarmed 1900MHz and without AWS.
My IMEI is listed in the status section.
What I've tried:
Before doing any modding of my phone, I previously backed up my EFS/IMEI with Andromizer (XDA link). Restoring it hasn't changed anything.
Changing network modes (LTE/WCDMA, LTE/GSM/WCDMA, GSM/WDCMA preferred)
Enabling/disenabling data roaming
Changing APN settings (The choices were T-Mobile US and T-Mobile US LTE)
So would flashing Tmobile radios help? Tmobile/d2tmo ROMs?
TL;DR: MY ATT I747 ON TMOBILE WONT KEEP THE H+ OR 3G SIGNAL AND IT SUCKS AND MAKES ME WANT TO CRY. PLZ HELP PLZ PLZ PLZ
Seriously though, any help would be appreciated. Thanks everyone! If you need anymore info Just let me know.

That "free" unlock method always made me suspicious and I've seen other complaints like this...
Sent from my SAMSUNG-SGH-I747 using xda premium

You may want to try flashing t-mo radio/modem. Do a nandroid first.
Sent from my SGH-I747 using xda app-developers app

gotmilk702 said:
That "free" unlock method always made me suspicious and I've seen other complaints like this...
Sent from my SAMSUNG-SGH-I747 using xda premium
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This is pretty frustrating. I changed my modems to an older ATT one, and now I only get 3G sporadically and 90% of the time its on G. So odd...
Also I'm pretty sure I'm specifically not supposed to flash a T-mobile modem....

davidjavid said:
This is pretty frustrating. I changed my modems to an older ATT one, and now I only get 3G sporadically and 90% of the time its on G. So odd...
Also I'm pretty sure I'm specifically not supposed to flash a T-mobile modem....
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Im so sorry i misread the OP...
Did you check your APN settings?

metalsnakebite said:
Im so sorry i misread the OP...
Did you check your APN settings?
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Yep, I checked them.... I tried a few different ones with the same results.Thanks for replying! There are some updates to the situation:
New thread.

[Q] Galaxy s3 att unlocked.. All ROM show 3G

Hi i have Galaxy s3 ATT i747 unlocked and every ROM i install give me 3G.. If i leave stock ROM it gives me 4G with know problems.. Is there any fix i can do that will give me 4G and modem i can install. Im on tmobile network

Can you see your IMEI number? I lost mine while flashing roms and the network couldn't recognize my phone, so it booted me down to 3g (but I'm on ATT).
jamiefff said:
Hi i have Galaxy s3 ATT i747 unlocked and every ROM i install give me 3G.. If i leave stock ROM it gives me 4G with know problems.. Is there any fix i can do that will give me 4G and modem i can install. Im on tmobile network
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Ozark_8125 said:
Can you see your IMEI number? I lost mine while flashing roms and the network couldn't recognize my phone, so it booted me down to 3g (but I'm on ATT).
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Yes I can see my imei
Sent from my SGH-I747 using xda app-developers app

Do your roms have the correct apn's?

I'm having connectivity challenges when trying 4.2.2 roms on Rogers w/ my i747m.
Tried most of the recommended modems on for i747m (complete modem list) http://forum.xda-developers.com/showthread.php?t=1831898
with CM10.1 and AOKP Task650.
The result, at worst little to no connectivity, at best intermittent connectivity. It doesn't seem to want to switch between towers and getting connectivity better than gprs or edge is pretty much non-existent
When I burn the rooted Rogers ROM - root66_RWC_I747MVLDLK4.tar.md5 I get good connectivity switching and 3G. I haven't seen LTE yet but it was only officially rolled out here 9 days ago so it's still crap and only partially out.
I'm about to roll back to the rooted ROM and apply the latest Canadian patch via KIES and give up on S3 mods. If some kind canadian has the time or inclination a faq/step by step on a S3 rogers install that actually works would be very appreciated. I've tried most of the recipes on XDA, task650, cyanomodgen and can't seem to come up with a working combination that gives me data/phone service that is at least as good as stock.
thanks,
rf

jamiefff said:
Hi i have Galaxy s3 ATT i747 unlocked and every ROM i install give me 3G.. If i leave stock ROM it gives me 4G with know problems.. Is there any fix i can do that will give me 4G and modem i can install. Im on tmobile network
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This may be correct. Do other ROMs switch between 3G and H+? Do you see 4G vice 4G LTE on stock rom? What download speeds are you getting on stock and other ROMs? With AT&T, HSPA was labeled 4G instead of H or H+. They had to add LTE to the 4G after LTE went online for them in order to differentiate a difference. The majority of places have HSPA labeled as H or H+ and LTE is considered true 4G. I have noticed that many ROMs will show 3G until data is received/sent and it switches to H+.

[Q] Stopped getting 4G after CM flash

i unlocked a sgh-i747 sgs3 for use on tmobile. when i was stock, i could get 4G and Edge only. After a suggestion, i updated my phone and it connected to all manner of 4G and HSPA networks.
i decided that i wasnt happy with the ROM and upgraded to CM 10.1.2-d2att by means of CWM v6.0.3.1.
after getting this happily flashed, i loaded CM and am now stuck in 3g.
any ideas???

I may be wrong, so don't try it without confirmation, but if you don't touch the radios, don't you need the t-mobile roms rather than the at&t ones? I suspect the problem using an at&t Rom is your apn's are messed up. Also check the order your networks try.
Sent from my SAMSUNG-SGH-I747 using Tapatalk 4

rdoac said:
but if you don't touch the radios
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can you elaborate on this? i know what a radio is, but i don't know if i follow you. as someone pretty new to all this, i feel that i did mess with the radio in order to get the AT&T phone, before i installed CM, to connect properly to the 3G signals.

In recovery you can flash modems and baseband. These are specific to the hardware in your phone. You should only flash ones specific to your model number. However the Roms are basically the same between different versions of the phone but with minor changes (at least between t mobile and at&t). There was a thread around explaining how to use a t mobile Rom on an at&t phone.
Sent from my SAMSUNG-SGH-I747 using Tapatalk 4

i tried to straight flash the tmobile rom and the little android guy died
rofl
meh... im in a bad place. i can't flash the CM i want because apparently the bootloader that fixes the 3G issue for me is based on ICS. if i update the bootloader so i can get the good CM, i guess i lose the fix... right now, i've reverted to the touchwiz that comes with the fix i talked about in my OP and 4G works properly again.
rock and a hard place.

Am glad you got something working. Can you sell that gs3 and get the T Mob version? If it were me, I'd probably stick with a touch wiz version for a while.
I'll try and read up some tomorrow.
Sent from my Nexus 7 using Tapatalk 4

rdoac said:
Can you sell that gs3 and get the T Mob version?
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heh, i just bought it. got it this morning from the post office! it was the cheapest one i could get given certain circumstances. you're right, it would be so much easier to just have the official tmobile version.
i have it back in CM now, but it's CM10.0.*. android 4.1 i think. and i'm getting HSPA+ with it. my biggest issue is that 3G fix... it sticks me on a ICS bootloader and that holds back the CM version from being anything 10.1.*. but at least i'm running CM now, even if it's not 4.2.

Tmobile note 3 slow lte on att

Just made the switch over to att and I am getting really slow lte speeds. Can anybody help?

Fix your APN?
sent from my sm-9005.

@rbiter said:
Fix your APN?
sent from my sm-9005.
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Tried every APN setting possible already. Searched all the threads and still no help.

There's a thread on here about flashing the AT&T modem and it solving the problem. Plz search and find it...
Here I found it for you..
http://forum.xda-developers.com/showthread.php?t=2522282
Sent from my SM-N900T using XDA Premium 4 mobile app

AdmiralCF420 said:
There's a thread on here about flashing the AT&T modem and it solving the problem. Plz search and find it...
Here I found it for you..
http://forum.xda-developers.com/showthread.php?t=2522282
Sent from my SM-N900T using XDA Premium 4 mobile app
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Thanks for the advice but I read through the thread already and it doesn't seem like it will improve drastically. So I rather not attempt to flash a modem that may cause a soft brick. My brother has a N900a and gets almost triple the speed of my lte. What gives?

I dont always get fast speeds. I'm guessing at&t phones get higher priority than other phones. There is a build.prop that you can flash/edit that may or may not work. I, myself, haven't made any mods because I get higher speeds usually. Not always. I am on a 900T but using an international 9005 rom with T-Mobile modem still. It really boils down to is the risk flashing a modem or build.prop worth it. In downtown houston I rarely dip below 10mb/s on LTE and occasionally see over 20mb/s. The congestion is real bad here so it is very often I get bumped back down to hspa. Like I said, you have to weigh the risks. I am fine with how it is working now. My post probably hasn't helped you get you where you want to go but it may help you to be content with what you have or may consider flashing an international rom minus modem and see if that helps.
sent from my sm-9005.

I'm on straight talk att sim and it's ridiculous on an att phone I get att quality signal. But with this tmobile phone when home I can only get signal in my bed room by the window . From I walk into building calls and signal dropped dead . It truly sucks. I'm switching back to tmobile as soon as this month is over . I hate paying that extra 30 dollars but a phone is no good in one room .
Sent from my SM-N900T using XDA Premium 4 mobile app

diamantericos said:
I'm on straight talk att sim and it's ridiculous on an att phone I get att quality signal. But with this tmobile phone when home I can only get signal in my bed room by the window . From I walk into building calls and signal dropped dead . It truly sucks. I'm switching back to tmobile as soon as this month is over . I hate paying that extra 30 dollars but a phone is no good in one room .
Sent from my SM-N900T using XDA Premium 4 mobile app
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I as well am on Straight Talk At&t micro sim and I get pretty decent speeds I believe Straight Talk cap's their LTE speeds at 15 down and I think around 8-9 up which ain't bad for the Chicago area. But there are times where I barely get 2 down and 4 up. I also have a Tmobile Note 3 stock/rooted using a ST sim.

nynexelf said:
I as well am on Straight Talk At&t micro sim and I get pretty decent speeds I believe Straight Talk cap's their LTE speeds at 15 down and I think around 8-9 up which ain't bad for the Chicago area. But there are times where I barely get 2 down and 4 up. I also have a Tmobile Note 3 stock/rooted using a ST sim.
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The speeds are fine when I actually get a signal . Its the fact that I have dead spots in almost my whole apartment except the rooms located to front of building . It was never like this before .
Sent from my SM-N900T using XDA Premium 4 mobile app

Tmobile Note 3 on ATT Network
I have a Tmobile unlocked phone on ATT and I can't find out anyway to speed up the LTE. I get LTE it seems, but it cuts the speed in half compared to my girlfriend ATT variant Note 3. I tried to flash an AT&T modem to it, but then it would soft brick the device and wouldn't boot. I have tried every APN I can think of, but still no success. I have tried the build.prop, like adding the lines for faster data tweak, but still nothing is getting better. I have full bars, but speed is slow. Do you have any suggestions on what to do, b/c I am out of options. Thanks.

Add me to the list. Just switched over to AT&T from T-mobile, but get very bad speeds. The only reason why I switched over was because with T-mobile, I was getting poor quality signal almost EVERYWHERE, so I had no choice.
I'm curious; if the bands in our phones support the proper AT&T bands and we actually get LTE, it's gotta be a software issue. Modem most likely.

Yeah im sure it has to do with the way the modem is optimized for ATT's 1700 band. I'm also in the same boat and have flashed ATT's modem but it doesn't work. Others have flashed ATT modems but I dont think anyone has been able to successfully see their baseband change in the settings so no one can say whether it worked for sure. I can tell you that the bars have nothing to do with your call signal though, its just your LTE signal strength. If you really want higher signal in your house if LTE seems to drop or be super slow, you should manually switch over to use HSPA+ in your house. Its a pain...i know.
I'm hoping eventually the newer modems fix the 1700 mhz frequency optimization or some devs figure out how to successfully flash N900A modems on the N900T.

LTE speeds
I have great signal almost always it seems like. I have full bars on LTE or 4G/HSPA+, but if I put my sim card in my AT&T variant note I get at least twice as much throughput than with the note 3 tmobile. It has to be a software issue, I have tried to flash att modems with no success. Just got to wait for a tweaked modem. I have even tried tweaking build.prop file and it works a little bit but not much. It is just weird I have full bars with LTE, but I won't be able to get data sometimes, which is really weird. I think there has to be something with the signal bars showing higher dbm that it actually is receiving. Probably another software glitch. Well if anyone has any insight on this issue let us know, please been looking everywhere.

LTE speeds
I think also that the modem is not the only issue. I flashed a kernel today after being on the stock kernel on the T-Mobile and I did a speedtest and the speeds were really low. Flashed another kernel and boom faster speeds back to where I was, maybe higher, but I will monitor to see what happens. But I read that Kernels do affect data speeds sometimes. I am just going to keep looking around to see if any kernels work.

stevestebo said:
I think also that the modem is not the only issue. I flashed a kernel today after being on the stock kernel on the T-Mobile and I did a speedtest and the speeds were really low. Flashed another kernel and boom faster speeds back to where I was, maybe higher, but I will monitor to see what happens. But I read that Kernels do affect data speeds sometimes. I am just going to keep looking around to see if any kernels work.
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Click to collapse
AFAIK it has nothing to do with kernel I might be wrong its just the modem
Sent from my SM-N900T using Tapatalk

Steven
Is there any tweaks that can be done to kinda help the LTE or at least fix my signal bars showing full all the time. I am thinking it is not switching towers when it is supposed to and giving a false signal strength. Is there anything on modifying like you can on Sprint phones with dbm on wimax, where it will switch antennas.

Has anybody flashed the new N900T NE6 based ROMs / modem and seen any difference?

dirrtyswan said:
Has anybody flashed the new N900T NE6 based ROMs / modem and seen any difference?
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I upgraded the modem and bootloader to the new NE6 version. I'm on Temasek CM11. My observations:
Signal strength is slightly better. Speeds are definitely much better. Prior to the upgrade, I'd get around 6-15/down, 3/up. Now I consistently get 25/down, 10/up.

ajm786 said:
I upgraded the modem and bootloader to the new NE6 version. I'm on Temasek CM11. My observations:
Signal strength is slightly better. Speeds are definitely much better. Prior to the upgrade, I'd get around 6-15/down, 3/up. Now I consistently get 25/down, 10/up.
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How did you get the new modem to stick? Did you do the triangle away method? If so, did you have to revert to a stock kernel first? I'm trying to upgrade only the modem and leave the bootloader as is. Is that a bad idea?

dirrtyswan said:
How did you get the new modem to stick? Did you do the triangle away method? If so, did you have to revert to a stock kernel first? I'm trying to upgrade only the modem and leave the bootloader as is. Is that a bad idea?
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It's getting incredibly frustrating to have to repeat this a number of times. I think this morning I had to repeat it already 3 times. Please do a search; there are plenty of pointers on how to get it done. For reference, here is what I did.
http://forum.xda-developers.com/showpost.php?p=52904005&postcount=95