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What modem should I flash to use a T-Mobile S4 (m919) on At&t network?

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abovenbeyond
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Default What modem should I flash to use a T-Mobile S4 (m919) on At&t network?

So I have am using already a T-Mobile S4 (m919) on At&t's network... I have already rooted it, flashed Hyperdrive, entered the correct APN, and it works basically well...

Here is what I am wondering, my signal strength seems to be not the best and it makes me wonder, is there a modem, baseband I can flash on the T-mobile version of the S4 that could possibly help it work better on the At&t network... and do so with out making my S4 a paper weight?
Current Phone: Galaxy S5 on AT&T.
Previous 4 phones: Galaxy S2, S3, S4, & Note 2!
 
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Quote:
Originally Posted by abovenbeyond View Post
So I have am using already a T-Mobile S4 (m919) on At&t's network... I have already rooted it, flashed Hyperdrive, entered the correct APN, and it works basically well...

Here is what I am wondering, my signal strength seems to be not the best and it makes me wonder, is there a modem, baseband I can flash on the T-mobile version of the S4 that could possibly help it work better on the At&t network... and do so with out making my S4 a paper weight?
Any M919 modem. MKL is the newest.
 
pahick
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Originally Posted by abovenbeyond View Post
So I have am using already a T-Mobile S4 (m919) on At&t's network... I have already rooted it, flashed Hyperdrive, entered the correct APN, and it works basically well...

Here is what I am wondering, my signal strength seems to be not the best and it makes me wonder, is there a modem, baseband I can flash on the T-mobile version of the S4 that could possibly help it work better on the At&t network... and do so with out making my S4 a paper weight?
Glad someone asked that. I looked for a few hours last night and came up empty(been working an off shift so I might have missed it). I am on 4.2.2 MDL and signal is definitely much weaker than my Active on 4.3 . Has anyone compared modems to see which are better?
 
lordcheeto03
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Originally Posted by pahick View Post
Glad someone asked that. I looked for a few hours last night and came up empty(been working an off shift so I might have missed it). I am on 4.2.2 MDL and signal is definitely much weaker than my Active on 4.3 . Has anyone compared modems to see which are better?
I can provide anecdotal evidence but nothing real...

MK2 is better.


Also, as for which modem to flash; T-Mobile's MK2 would be the one to flash. I've read you can flash other carrier's modems as long as they are the same version, i.e. AT&T MK2 or T-Mobile MK2... but that just doesn't make sense to me and I wouldn't recommend it. The modem you flash is independent of who your carrier is; you go by what brand of phone you have. If you have the M919 then you flash T-Mobile firmwares/modems/etc regardless of which carrier your bill comes from.
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Originally Posted by abovenbeyond View Post
Here is what I am wondering, my signal strength seems to be not the best and it makes me wonder, is there a modem, baseband I can flash on the T-mobile version of the S4 that could possibly help it work better on the At&t network... and do so with out making my S4 a paper weight?
I've encountered the same thing with my M919. Switching between Android 4.3 and 4.4.2 modem.bin files made no difference.

I did notice that when I changed my network preference from 3G/2G to 2G-only, I gained about 10 dBa when the handset fell back to GSM-EDGE mode. It made a big difference. I verified that AT&T only uses band II (1900MHz) for GSM and UMTS in my county, so it wasn't because I switched to band V (850MHz) which seems to have better range. What I find annoying is that the handset isn't dropping down to 2G automatically when reception is poor. It'll stick with 3G even when the signal strength is as low as -107 dBa.

No LTE at the moment since my AT&T MNVO doesn't support it.
 
Frankenscript
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I'm thinking of buying an M919, carrier unlocked, to use on ATT, so that I can get a proper recovery and have full access to custom ROMs without the safestrap limitations.

Is it safe to say that:
1. If I buy a T-Mobile S4, and it comes carrier unlocked, it will work fine on the ATT network, including 4G / LTE? Lots of data points suggest this but I haven't heard it explicitly stated...
2. Though I could use the phone as identified as an M919, I really want Play Store to see it as an I337 (ATT version), so I can install some ATT specific apps. Is there any problem flashing a build.prop (available in the ATT threads) with the ATT identifiers & APN info, to enable this?
3. Are there any gotchas I should be aware of? Basically, I just want a phone with unlocked bootloader / kernel so I can play. Not too worried about Knox/warranty.

Any insights would be appreciated!

Marc
Current Phone:
T-Mo M919 / MDL bootloader / NB4 modem baseband /
Getting Dirty with: Dirty Unicorns


Previous phone:
ATT I337 / NC1 / SafeStrap 3.72 / GoldenEye v36

Other:
ASUS TF701T (rooted stock 4.3)
SAMSUNG Tab2 10.1 WiFi (stock 4.2.2)
SAMSUNG Tab2 10.1 WiFi (SlimKat... awesome!)
 
lordcheeto03
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Originally Posted by Frankenscript View Post
I'm thinking of buying an M919, carrier unlocked, to use on ATT, so that I can get a proper recovery and have full access to custom ROMs without the safestrap limitations.

Is it safe to say that:
1. If I buy a T-Mobile S4, and it comes carrier unlocked, it will work fine on the ATT network, including 4G / LTE? Lots of data points suggest this but I haven't heard it explicitly stated...
2. Though I could use the phone as identified as an M919, I really want Play Store to see it as an I337 (ATT version), so I can install some ATT specific apps. Is there any problem flashing a build.prop (available in the ATT threads) with the ATT identifiers & APN info, to enable this?
3. Are there any gotchas I should be aware of? Basically, I just want a phone with unlocked bootloader / kernel so I can play. Not too worried about Knox/warranty.

Any insights would be appreciated!

Marc
Will the T-Mobile S4 work on the AT&T network; yes it will work if it's carrier unlocked. I purchased my M919 full price out of contract while I was still on AT&T service. Once I carrier-unlocked I was able to pick up AT&T's 4G/LTE and was even able to make use of the AT&T 3G Microcell device which transmits a 3G cell signal and runs over your WiFi. I now have Net10 Wireless with an AT&T SIM card and I still get 4G/LTE when it's around.

Your second question: I do believe that's all that would be required. I'm not 100% sure if just modifying the build.prop would allow you to use the AT&T-specific apps in the Play Store. I never used them to begin with so I never explored whether or not I could make them work on the T-Mobile firmware. Now, I know this involves more than just a build.prop edit, but a 100% sure way to get AT&T Apps working would be to flash a custom ROM based on AT&T firmware. Being that you have a T-Mobile device and are using it on another carrier's network, always remember; when it comes to Odin especially, flash things meant for the T-Mobile M919 ONLY. It doesn't matter that you use AT&T service, your device needs T-Mobile Modems/stock firmwares/etc.

As far as gotchas... not that I can think of. The M919 has an unlocked bootloader and even with KNOX is very easy to root and use custom ROMS on. If you're not concerned with KNOX then you really don't have to take into consideration any special rooting method, no safestrap junk, etc. Without root, just flash a recovery in Odin and flash away.
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