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[Q] No Service after unlock

I successfully unlocked my Samsung Galaxy S 4G. However when I insert an AT&T sim, I show full bars of signal but the screen says (No Service). I've tried two different sim cards and neither will work. They are both older sim cards but they should still work, right?
Only thing that stands out as odd is the AT&T APN isn't checked blue; it's white (unmarked?) and can't be selected. I'm using Gingerbread 2.3 and my T-Mobile card works fine. I have my network bands set to automatic.
And for the record, in order to connect to AT&T's network, I need to use the AT&T sim all the time, right? I won't be able to connect to AT&T when using the T-Mobile sim, yes?

Tmobile cam connect to AT&T only when data roaming for me if I got to arkansas... Im.at&t. But imma say to try to unlock again
Sent from my SGH-T959V using XDA App

mcbipolar said:
I successfully unlocked my Samsung Galaxy S 4G. However when I insert an AT&T sim, I show full bars of signal but the screen says (No Service). I've tried two different sim cards and neither will work. They are both older sim cards but they should still work, right?
Only thing that stands out as odd is the AT&T APN isn't checked blue; it's white (unmarked?) and can't be selected. I'm using Gingerbread 2.3 and my T-Mobile card works fine. I have my network bands set to automatic.
And for the record, in order to connect to AT&T's network, I need to use the AT&T sim all the time, right? I won't be able to connect to AT&T when using the T-Mobile sim, yes?
Click to expand...
Click to collapse
When you switch Sim cards you have to do a factory data reset. Just enter recovery and select the option to factory reset then reboot it should recognize your new Sim.
Sent from my SGH-T959V using XDA Premium App

I did a factory data reset from Settings->Privacy->Factory Data Reset and it didn't work. Still says No Service.
And I don't think I need to unlock again because when I access that one screen (I forget the code to enter) it shows all the locks as set to OFF.
Any other ideas why the AT&T SIM card won't allow my phone to connect? Is the fact that it's an old card the problem?

mcbipolar said:
I did a factory data reset from Settings->Privacy->Factory Data Reset and it didn't work. Still says No Service.
And I don't think I need to unlock again because when I access that one screen (I forget the code to enter) it shows all the locks as set to OFF.
Any other ideas why the AT&T SIM card won't allow my phone to connect? Is the fact that it's an old card the problem?
Click to expand...
Click to collapse
It could be the sim card although I really dont see how it could be. Is it a 3g sim card? If so it should still work, factory reset, input the at&t apn settings, reboot phone. That is what I would try, I have an unlocked phone as well, and once you input the unlock code, its UNLOCKED.

type in *#06# and let me know what comes up

jdubb1106 said:
type in *#06# and let me know what comes up
Click to expand...
Click to collapse
Didn't think of that, depends how it was unlocked. IMEI could be issue

mcbipolar said:
I successfully unlocked my Samsung Galaxy S 4G. However when I insert an AT&T sim, I show full bars of signal but the screen says (No Service). I've tried two different sim cards and neither will work. They are both older sim cards but they should still work, right?
Only thing that stands out as odd is the AT&T APN isn't checked blue; it's white (unmarked?) and can't be selected. I'm using Gingerbread 2.3 and my T-Mobile card works fine. I have my network bands set to automatic.
And for the record, in order to connect to AT&T's network, I need to use the AT&T sim all the time, right? I won't be able to connect to AT&T when using the T-Mobile sim, yes?
Click to expand...
Click to collapse
you would need to use your att sim card you may have a issue with the fact the sgs4g actually lacks 3g band
its hsdpa or edge or G
unless att uses the same spectrum as tmobile for hsdpa you prob will not get a signal

Thanks for the help everyone. In my newbishness, I didn't understand from the instructions on unlocking that the foreign SIM needed to be active. None of the instructions say it needs to be. That turned out to be the problem: I was using an old, inactive SIM (hence no service).
Sick as I am with T-Mobile, I just took my phone in to AT&T and switched providers yesterday.

Nexus 5 was on R+ CDMA - Now ST SIM gives no signal

When I go into the settings for Mobile networks at the bottom where it says System select it says change the CDMA roaming mode. the problem is I reset the phone and it now has a ST AT&T SIM card in it. Why does it still think it is CDMA?

mobileboost said:
When I go into the settings for Mobile networks at the bottom where it says System select it says change the CDMA roaming mode. the problem is I reset the phone and it now has a ST AT&T SIM card in it. Why does it still think it is CDMA?
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Click to collapse
Same exact thing happened to me. When I was researching the problem I came across this thread. The phone was showing no signal and then suddenly it received a SMS message saying my phone was ready to use. I rebooted it and it's fine, full signal. To people experiencing this, I suggesting waiting for about an hour and maybe your phone will cure itself too.

[Q] Bought used phone, won't activate with new sim from verizon

Hey M8 crew!
New to the M8, just bought the phone from swappa. Apparently it has root/s-off/some lollipop build installed on it. Clean ESN.
Took it into verizon to activate it on my line, but the sim doesn't appear to activate as they expect. It detects that it was inserted, says to reboot, after reboot still says no service, and never performs any activation. Verizon rep was claiming that the rom was causing the failures, and it does appear to likely be software related if it is never launching the activation. VZW tech support was no help other than saying it may take up to 12 hours to activate the sim (bs meter going off). Spent 2 hours in the store trying to get it to activate, saying everything was fine on their end. Tried a couple sims in store to rule out a bad sim. Have even tried the tape on the sim trick to see if that might have something to do with it.
Has anyone ever seen / heard of this sort of situation before and have any idea of how to fix it?
Would a stock RUU flash help out in anyway?
Is it because it is not a verizon rom that the activation is not happening? Would I somehow be able to use a different verizon phone to activate the sim, then put it in my phone and have service start working?
Any ideas?

nectur said:
Hey M8 crew!
New to the M8, just bought the phone from swappa. Apparently it has root/s-off/some lollipop build installed on it. Clean ESN.
Took it into verizon to activate it on my line, but the sim doesn't appear to activate as they expect. It detects that it was inserted, says to reboot, after reboot still says no service, and never performs any activation. Verizon rep was claiming that the rom was causing the failures, and it does appear to likely be software related if it is never launching the activation. VZW tech support was no help other than saying it may take up to 12 hours to activate the sim (bs meter going off). Spent 2 hours in the store trying to get it to activate, saying everything was fine on their end. Tried a couple sims in store to rule out a bad sim. Have even tried the tape on the sim trick to see if that might have something to do with it.
Has anyone ever seen / heard of this sort of situation before and have any idea of how to fix it?
Would a stock RUU flash help out in anyway?
Is it because it is not a verizon rom that the activation is not happening? Would I somehow be able to use a different verizon phone to activate the sim, then put it in my phone and have service start working?
Any ideas?
Click to expand...
Click to collapse
If the phone was used on another carrier it might be stuck in a non lte/CDMA mode. Flash stock vzw ruu. Do a factory reset. Go into mobile settings and make sure it's set to global. Then see if default network is set to vzw. Then check provisioning.

That did it. Thanks!

nectur said:
That did it. Thanks!
Click to expand...
Click to collapse
Np...bought an m8 for my dad a couple months back and same thing happened. I finally realized it was used on a different carrier.

[Q] Phone wont stay on LTE

I recently switched from straight talk to verizon's own pre paid plan after being fed up with straight talk. When I first got the service active everything was fine. I flashed the CM11 AOSP rom snapshot. I then proceeded to try and update my roaming capabilities by dialing *228 which the automated system told me was successful and ever since then my phone will not stay on LTE. It will only goto 3G. If i try to force the lte only mode then my data will work but i wont be able to make calls. I have tried going into stock recovery and resetting factory to try and clear the NV and flashing both the kitkat and lollipop RUU to no avail. Any help would be greatly appreciated.

You might have damaged your Sim card by dialing *228, well I don't know about damaged, but I know Verizon phones locked to their network that uses 4G LTE Sim cards are blocked from dialing *228 because of the reasons you described.

rigbyrobot said:
You might have damaged your Sim card by dialing *228, well I don't know about damaged, but I know Verizon phones locked to their network that uses 4G LTE Sim cards are blocked from dialing *228 because of the reasons you described.
Click to expand...
Click to collapse
So maybe i need to go get a new sim card then. Thats what i figured hopefully i can get to the verizon store before work and grab one.

Hey,
Were you able to get it working again?
I have the same issue. I dialed *228 like an idiot and my phone activated on 3G and won't get anything else.
I've had Verizon reset the connection on their side and I went to the store and picked up a new SIM but I still can't get LTE. It's driving me crazy. I've tried restoring to a prior backup, factory resetting the phone. Nothing gets me LTE.

Unlocked T-Mobile Data and Reception Dropping in and Out

I picked up an unlocked T-mobile G5 and I'm using it for AT&T... The rep at the store applied the APN setting for ATT but I noticed after I got a new SIM installed and went home the reception and data connection started dropping in and out.
Basically, when the phone is sleeping and then I wake it starts searching for network then gets reception then get a signal for a couple mins then drops again and searches. Since it's a T-Mobile phone on an ATT network is there certain settings that I need to turn off like VoIP, WIFI calling etc? Any ideas?

Wipe out all existing APNs and start from scratch? Use the NXTGENPHONE APN. I'm using an unlocked T-Mobile H830 LG G5 on AT&T and I have no problems. My sister's Nexus 6 uses the same APN no problems either.
https://www.att.com/esupport/article.html#!/wireless/KM1062162

smartnphone said:
Wipe out all existing APNs and start from scratch? Use the NXTGENPHONE APN. I'm using an unlocked T-Mobile H830 LG G5 on AT&T and I have no problems. My sister's Nexus 6 uses the same APN no problems either.
https://www.att.com/esupport/article.html#!/wireless/KM1062162
Click to expand...
Click to collapse
So I followed your steps.. I wiped all existing APNs and entered the APN setting in the link you provided and used the NXTGENPHONE APN but I couldn't get data but just had reception to make calls. So I changed the name to AT&T and the APN name to phone and I get data and reception but it still drops in and out.
I went to ATT to see what they could suggest but the only thing they offered was maybe a faulty SIM card and switched it out but it's still doing the same thing... Has anyone experienced this? Should I do a factory reset maybe? If I do that, I won't lose SIM unlock right?

sguerra923 said:
So I followed your steps.. I wiped all existing APNs and entered the APN setting in the link you provided and used the NXTGENPHONE APN but I couldn't get data but just had reception to make calls. So I changed the name to AT&T and the APN name to phone and I get data and reception but it still drops in and out.
I went to ATT to see what they could suggest but the only thing they offered was maybe a faulty SIM card and switched it out but it's still doing the same thing... Has anyone experienced this? Should I do a factory reset maybe? If I do that, I won't lose SIM unlock right?
Click to expand...
Click to collapse
I was going to suggest a factory reset as a last resort. You won't lose the sim unlock; it's permanent unlock.
Troubleshooting is the name of the game and you'll have to keep having to try potential solutions until it's fixed.
Hopefully it's not a hardware issue with the radio or you'll have to swap it out and reunlock it all over again.

are you on 10A or 10D?
10D seems to improve the radio... but if you wan root/twrp make sure you do all that on 10A first before upgrading to 10D.
also, have you tested the phone in different areas? or just at your house and immediate area? perhaps it's just an issue in specific locations? what if you drive across town or something?

smartnphone said:
I was going to suggest a factory reset as a last resort. You won't lose the sim unlock; it's permanent unlock.
Troubleshooting is the name of the game and you'll have to keep having to try potential solutions until it's fixed.
Hopefully it's not a hardware issue with the radio or you'll have to swap it out and reunlock it all over again.
Click to expand...
Click to collapse
Performed a factory reset and issue is still there but slightly improved but I need to test it more... Basically, when I wake the phone it searches for network (not all the time but here and there) then locks a signal..

autoprime said:
are you on 10A or 10D?
10D seems to improve the radio... but if you wan root/twrp make sure you do all that on 10A first before upgrading to 10D.
also, have you tested the phone in different areas? or just at your house and immediate area? perhaps it's just an issue in specific locations? what if you drive across town or something?
Click to expand...
Click to collapse
In on 10D.. Yeah I tried it in different areas and driving when I'm art a stoplight I can see it searching for network.. I switched the SIM card and did a factory reset any other suggestions?

Is your Network mode set to GSM/WCDMA/LTE auto? If it's not area specific it might be hardware related.
How did you get the 10D update on AT&T btw?

smartnphone said:
Is your Network mode set to GSM/WCDMA/LTE auto? If it's not area specific it might be hardware related.
How did you get the 10D update on AT&T btw?
Click to expand...
Click to collapse
Yes, my network mode is set to that setting. The person I purchase this phone from had T-Mobile and updated before they sold it to me.

sguerra923 said:
Yes, my network mode is set to that setting. The person I purchase this phone from had T-Mobile and updated before they sold it to me.
Click to expand...
Click to collapse
Last thing to try is Mobile networks>Network operators>Search networks. Maybe manually choosing one might help? Enable Data Roaming?
Could be a hardware issue if not software.

smartnphone said:
Last thing to try is Mobile networks>Network operators>Search networks. Maybe manually choosing one might help? Enable Data Roaming?
Could be a hardware issue if not software.
Click to expand...
Click to collapse
Yeah, I tried that too.. Got back from Tmobile and they said that another person experienced the same issue couple weeks ago and they said that some G5s that are unlocked and used on different networks are still trying to jumping back on the tmobiles phone network hence my phone searching signals off and on...

Just wanted to give another confirmation that the LG-H830 works perfectly on AT&T (H83010D [BL,modem,system], rooted, unlocked). I gave up on Verizon and my fiancé now uses it on AT&T. She loves it!

Geez.. I got scammed. The person looks like they file a insurance claim on the phone so my ESN is blacklisted! Great! Lesson learned the hard way. Any suggestions what I can do? I saw that people are buying bad ESN phone on ebay as long as I post that it's a bad ESN.

OP, I had the exact same problem on T-Mobile after doing a temporary unlock. I took it to a T-mobile store and they tried swapping the SIM but that didn't help so they did a warranty replacement. Two days later I had a new phone and everything works again. I didn't (and won't) try to SIM unlock it again.
Sent from my LG-H830 using XDA-Developers mobile app

I have heard of people getting past blacklist. Think you can pay to fix it.
---------- Post added at 11:14 PM ---------- Previous post was at 11:13 PM ----------
Are you guys not changing the apns xml file????? Or enable roaming and setting rat to global?

jhasty01 said:
I have heard of people getting past blacklist. Think you can pay to fix it.
---------- Post added at 11:14 PM ---------- Previous post was at 11:13 PM ----------
Are you guys not changing the apns xml file????? Or enable roaming and setting rat to global?
Click to expand...
Click to collapse
I did some research online on blacklist repairs but do you or can anyone give me some recommendations on it? Sucks cause even if I get it repaired I wondering if I still will have issues with the reception..
Anyone tried this site? http://www.imeifix.com/

I just tried the sim unlock as well. I'm a tmobile customer so I really didn't have a reason to do it. Just wanted to see if it would unlock.
Well it said it could not be unlocked and I, out of dumb curiosity tried the temporary unlock. It worked and said it is unlocked until August. I think roughly 30 days after I did it.
Well, later that day or the next my phone started doing the same exact thing. Signal dropping and searching. Furthermore though, I woke up to a warm phone today. Same as it gets when doing lots of app updates. I unplugged it from the charger and watched the battery drop 4% in only 15 minutes of standby (screen off, not using the phone).
I just flashed it back to stock and relocked the boot loader and will see if it fixed it. Was running rooted 10d when this happened.
I'm starting to think that sim unlock app is evil or something. I haven't put my sim card back in as of yet but will update if it starts acting up when I do.
Possible explanation?:
I noticed a T-Mobile diagnostic app try to gain root access during the weirdness which I had never seen before. Maybe the sim unlock gains a sudo root to do the unlock but on a rooted phone with a non stock root manager causes the unlock app to endlessly loop trying to gain access and thus cause a warm phone and signal dropouts? Just a hunch but would be interested to see what others think.
*** Ok so quick update, I put my tmobile sim back in and the signal is dropping in and out again. The phone worked fine before I tried the unlock. This is so uncool.
Sent from my LG-H830 using XDA-Developers mobile app

I think I may have isolated the cause. I disabled the device unlock app in app settings and rebooted. Since then I haven't noticed the signal drop out.
EDIT: Yeah, that's a big nope. I'm still experiencing the problem after a total wipe and reflashing using LGUP refurbish mode. It's still dropping in and out, sometimes three times per minute. +1 to never use device unlock app.
I'm on stock unrooted 10d btw.
Oh, and the same SIM card works just fine in my older phones.
Sent from my LG-H830 using XDA-Developers mobile app

For what its worth, Att doesn't use the exact same bands as t Mobile....you might want to research some threads on the Att LG G5.