Related
I did the OTA root of my phone earlier this week and applied the Fresh ROM and the WiMax Radio Update. After that my WiMax stopped working. I get "Connected to Sprint" , "Disconnected" , back to Scanning. I did notice that my WiMax MAC was not correct and followed the steps using the adb commands to correct it. This still did not solve the WiMax connection issues.
I spent a good amount of time yesterday trying to "unroot" the phone and go back to stock. The RUU methods weren't working because of bootloader version issues. I finally found some advice here to to use Toasts Step 2 Method to downgrade the bootloader. This worked and I was able to then apply the Stock ROM using the RUU File RUU_Supersonic_1.32.651.1_Radio_1.39.00.04.26_release_171253
After getting back to stock I allowed all the OTA updates to apply. I'm still having the same WiMax 4G issue. The WiMax radio turns on, goes to scanning, connecting, disconnected, scanning.
I called Sprint last night and they had me do a ##786# reset with my MSL code, PRL Update, Profile Updates, etc. They also tried having CC remove the 4G services and re-provision. I'm still stuck with out the ability to connect to WiMax.
Before I return the phone ... anyone else have any suggestions I should try?
Appreciate the help.
ksujace said:
I did the OTA root of my phone earlier this week and applied the Fresh ROM and the WiMax Radio Update. After that my WiMax stopped working. I get "Connected to Sprint" , "Disconnected" , back to Scanning. I did notice that my WiMax MAC was not correct and followed the steps using the adb commands to correct it. This still did not solve the WiMax connection issues.
I spent a good amount of time yesterday trying to "unroot" the phone and go back to stock. The RUU methods weren't working because of bootloader version issues. I finally found some advice here to to use Toasts Step 2 Method to downgrade the bootloader. This worked and I was able to then apply the Stock ROM using the RUU File RUU_Supersonic_1.32.651.1_Radio_1.39.00.04.26_release_171253
After getting back to stock I allowed all the OTA updates to apply. I'm still having the same WiMax 4G issue. The WiMax radio turns on, goes to scanning, connecting, disconnected, scanning.
I called Sprint last night and they had me do a ##786# reset with my MSL code, PRL Update, Profile Updates, etc. They also tried having CC remove the 4G services and re-provision. I'm still stuck with out the ability to connect to WiMax.
Before I return the phone ... anyone else have any suggestions I should try?
Appreciate the help.
Click to expand...
Click to collapse
I am having the same exact problem, i was told its something deeper than just the MAC address problem, i would just get a warranty replacement or exchange your phone since youre within the 30 days.
I just installed Netarchy's Stock 2.2 with Root, then applied the radio updates he listed, doing WiMax last. My 4G just says "scanning" when I turn it on, and never actually connects. I am hoping the tower near me is just down at the moment, but I am doubtful.
After I check in a couple of areas if 4G is still not working, I will try reseting the phone and root it again, running the 2.2 w/root, without installing radio updates.
Other then my WiMax getting flushed, Froyo ROCKS. Battery is lasting much longer, better features, etc.
I updated my radios with:
Radio update: 2.15.00.07.28
and
Wimax Update 26023
This is all you have to do:
http://forum.xda-developers.com/showthread.php?t=715915
Only thing that worked for me, do this step, then install the ROM you had before. Like I said, only thing that works!
bigupurself7 said:
This is all you have to do:
http://forum.xda-developers.com/showthread.php?t=715915
Only thing that worked for me, do this step, then install the ROM you had before. Like I said, only thing that works!
Click to expand...
Click to collapse
I tried this ... started over all the way back to original RUU. Still no 4G. I took my phone to the Sprint Store today, left it for a tech to look at.
has anyone else heard of certificate issues that are used in WiMax authentication? I wonder if those certs were damaged by the radio updates. You'd think going back to stock RUU would repair that.
Maybe the stock RUU doesn't actually update the radio device?
If you have the latest radio and 4g is not working you need to flash the Rom again, just the Rom as the radio is already update.
Ps: remember do a titanium and or nandroid back up b4 flashing, good luck.
Sent from my Evo using XDA App
jahnile said:
If you have the latest radio and 4g is not working you need to flash the Rom again, just the Rom as the radio is already update.
Ps: remember do a titanium and or nandroid back up b4 flashing, good luck.
Sent from my Evo using XDA App
Click to expand...
Click to collapse
Flashed the ROM multiple times, still no luck.
ok have you tried a different rom? Just flash a different rom and test the wifi to see if you have the same issue. If it works then you know your issue was with the rom...
jahnile said:
ok have you tried a different rom? Just flash a different rom and test the wifi to see if you have the same issue. If it works then you know your issue was with the rom...
Click to expand...
Click to collapse
In my case flashing back to 2.1 stock, 4G worked again, no problem. But I want the 2.2... The thread for Netarchy's 2.2 stock rom with root has a few people having the same issue, but for most people it looks like the rom is working without WiMax issues.
ksujace said:
I did the OTA root of my phone earlier this week and applied the Fresh ROM and the WiMax Radio Update. After that my WiMax stopped working. I get "Connected to Sprint" , "Disconnected" , back to Scanning. I did notice that my WiMax MAC was not correct and followed the steps using the adb commands to correct it. This still did not solve the WiMax connection issues.
I spent a good amount of time yesterday trying to "unroot" the phone and go back to stock. The RUU methods weren't working because of bootloader version issues. I finally found some advice here to to use Toasts Step 2 Method to downgrade the bootloader. This worked and I was able to then apply the Stock ROM using the RUU File RUU_Supersonic_1.32.651.1_Radio_1.39.00.04.26_release_171253
After getting back to stock I allowed all the OTA updates to apply. I'm still having the same WiMax 4G issue. The WiMax radio turns on, goes to scanning, connecting, disconnected, scanning.
I called Sprint last night and they had me do a ##786# reset with my MSL code, PRL Update, Profile Updates, etc. They also tried having CC remove the 4G services and re-provision. I'm still stuck with out the ability to connect to WiMax.
Before I return the phone ... anyone else have any suggestions I should try?
Appreciate the help.
Click to expand...
Click to collapse
exact same prob. 2 days trying everything and have gotten nowhere. i guess we have a unique prob. so frustrated.
Sprint Store ordered me a warranty replacement after leaving it there yesterday for service.
ksujace said:
I did the OTA root of my phone earlier this week and applied the Fresh ROM and the WiMax Radio Update. After that my WiMax stopped working. I get "Connected to Sprint" , "Disconnected" , back to Scanning. I did notice that my WiMax MAC was not correct and followed the steps using the adb commands to correct it. This still did not solve the WiMax connection issues.
I spent a good amount of time yesterday trying to "unroot" the phone and go back to stock. The RUU methods weren't working because of bootloader version issues. I finally found some advice here to to use Toasts Step 2 Method to downgrade the bootloader. This worked and I was able to then apply the Stock ROM using the RUU File RUU_Supersonic_1.32.651.1_Radio_1.39.00.04.26_release_171253
After getting back to stock I allowed all the OTA updates to apply. I'm still having the same WiMax 4G issue. The WiMax radio turns on, goes to scanning, connecting, disconnected, scanning.
I called Sprint last night and they had me do a ##786# reset with my MSL code, PRL Update, Profile Updates, etc. They also tried having CC remove the 4G services and re-provision. I'm still stuck with out the ability to connect to WiMax.
Before I return the phone ... anyone else have any suggestions I should try?
Appreciate the help.
Click to expand...
Click to collapse
exact same prob. 2 days trying everything and have gotten nowhere. i guess we have a unique prob. so frustrated.
ipclark1 said:
exact same prob. 2 days trying everything and have gotten nowhere. i guess we have a unique prob. so frustrated.
Click to expand...
Click to collapse
Your 4g certificate keys got messed up. There is no known solution other than a replacement. I've been to Sprint, I've been online with HTC. There is no solution. Doesn't feel like there will ever be one.
rocolema said:
Your 4g certificate keys got messed up. There is no known solution other than a replacement. I've been to Sprint, I've been online with HTC. There is no solution. Doesn't feel like there will ever be one.
Click to expand...
Click to collapse
thanks ill go in tommorow for replacement....jeez i'm at my wits end. going to try one more factory reset-root-flash....then im throwing it at the wall.
I am having the same issue with several roms. I just keep going back to the 2.1 when it fails. I have tried every update for the radio I can find, I am going to try again with some new radio zips, but so far 4g is just not working on any 2.2 rom that I try.
I rooted my phone and loaded Caulkin's rom. Then I noticed I didn't have any service bars in an area I normally have full coverage. I tried other roms with the same results. Now I've unrooted and gone back to stock 3.70. I still have no service. I can place calls, but no calls come through, as if I'm in a dead zone. As soon as I place a call the bars come back up to there normal level for the area I'm in. When I rooted I used the autoroot 2.3 method. I have hardware version 004 with hboot 2.02. Has anybody heard of this issue, and is there a fix? Or do I need to consider going to sprint? Thanks in advance.
Hmmm I'm a newbie but sounds like u need to update Ur radios id search the board for install radios and see if that's the problem
Go http://forum.xda-developers.com/showthread.php?t=715485 and download and flash the latest radio; it should help.
Try updating your profile and prl from the settings menu. If you used the 3.70 ruu your radio will be up to date but you'll still have an old prl.
Sent from my PC36100 using XDA App
Profile and PRL
I've updated the profile, prl and I'm on the latest radio. I can still place calls intermittently, sometimes I have to reboot to make a phone call. But I still can't receive any phone calls. Thanks.
So my friend rooted his Evo with Unrevoked. I verified s-off.
He copied a PC36IMG onto his SD which turns out was some 2.1 rooted stock ROM. After doing that his phone could not make/receive calls/text or connect to 1x/3G/4G. Basically an expensive phone that has no phone functions. Everything else works (WiFi included). He flashed http://link.geekfor.me/rootedromzip onto his phone from http://forum.androidcentral.com/htc...vo-install-clockwork-recovery.html#post165998.
When I looked at it, he still did not have a custom recovery so I flashed Amon RA PC36IMG. Full factory wiped data/cache/dvalik. Flashed Synergy RC1. Phone still could not make/receive calls and was getting Error 16 when trying to call. Called Sprint and they reprovisioned phone and fixed calls and texting. Noticed his phone is stuck on 1x and cannot connect to 3G when my phone next to his works fine. Did not test 4G yet since I have poor 4G coverage in my area. Cannot update his profile - just sits there like something is happening but it never completes.
What are his options here? Is it a bad radio or something that we can fix? Can we flash a stock rooted ROM and regain 3G? Remember, no nandroid was made unfortunately.
I would try flashing the latest radios just to be sure. And tell your friend to always make a nandroid backup to avoid this problem in the future.
Well his first time flashing. I think he mistakenly thought the PC36IMG as a custom recovery but it was actually an entire ROM.
Didn't have a chance to nandroid. I'm instructing him how to update newest radio combo and seeing what happens.
Update: Flashed latest combo radio. Updated profile and PRL. Still stuck on 1x even after reboot. Is he hosed? Does Sprint have to do something on their end to fix his EVDO? 4G isn't working either by the way.
Update 2: Wimax Keys Checker - https://market.android.com/details?id=com.joeykrim.wimaxkeys says that RSA Key is present. Relieved that he didn't lose his RSA key. Just can't figure for the life of me why he can't connect to 3G or 4G. Not sure where to go from here? Maybe trying to flashing latest stock rooted RUU? http://forum.xda-developers.com/showthread.php?t=1110733
Bumping for some attention.
Hey, happened to me a couple of times, it will come back. Maybe wipe everything again, have you tried ##data# and entering msl key, wait... Have you updated his data profile in settings
Sent from my PC36100 using XDA Premium App
Hello.....did that work for ya?
Sent from my PC36100 using XDA Premium App
Ok, was on the road when I had wife reply...lol.. When you rebooted the phone,did you wipe cache,and dalvik. Then try updating profile? It sounds weird,but has worked for me,without even updating profile. I have had no coverage before after flashing a Rom,also,did just that,and it came back. If rsa keys are present,that is good. If you would be kind enough to reply,whether fixed or not,would appreciate it,anyway,gonna move on...
Sent from my PC36100 using XDA Premium App
Cares said:
So my friend rooted his Evo with Unrevoked. I verified s-off.
What are his options here? Is it a bad radio or something that we can fix? Can we flash a stock rooted ROM and regain 3G? Remember, no nandroid was made unfortunately.
Click to expand...
Click to collapse
Did he try updating his profile & prl
Sent from my criffvo
Updating profile and PRL doesn't work. It keeps attempting to update but it is never successful.
I haven't had a chance to get his phone to just try reflashing a new ROM or stock ROM to see what will happen though.
He says using ##data# and entering his MSL code and changing EVDO to automatic doesn't work either.
Cares said:
Updating profile and PRL doesn't work. It keeps attempting to update but it is never successful.
I haven't had a chance to get his phone to just try reflashing a new ROM or stock ROM to see what will happen though.
He says using ##data# and entering his MSL code and changing EVDO to automatic doesn't work either.
Click to expand...
Click to collapse
I would start over again ... wipe completely with Calkulin's "fomat all" zip and flash a rooted stock rom like xhausx. Once the phone boots up, call Sprint and have them walk you through provisioning everything. Once all is well, then move into whatever custom stuff he wants.
wmdunn said:
I would start over again ... wipe completely with Calkulin's "fomat all" zip and flash a rooted stock rom like xhausx. Once the phone boots up, call Sprint and have them walk you through provisioning everything. Once all is well, then move into whatever custom stuff he wants.
Click to expand...
Click to collapse
You took the words from my mouth!
Is he Flashing the RUU's or just running them through the computer? Normally, you sync your phone or through hBoot and then start the program, try flashing stock Froyo and then factory reset once flashed, it helps clear out traces of old roms etc. If you need anymore help feel free to ask, I would be more than happy!
I don't think it worked.
Calkulin's Format, flashed Odexed http://forum.xda-developers.com/showthread.php?t=1133379.
It showed 3G but I think it was misleading. Wiped and flashed to evodeck and it went back to showing 1x. My phone has 3G showing on evodeck next to his so he definitely has 3G coverage.
I guess it's just time to call Sprint for a re-provision? Does it have to be on a Sense ROM for them to reprovision?
Cares said:
I don't think it worked.
Calkulin's Format, flashed Odexed http://forum.xda-developers.com/showthread.php?t=1133379.
It showed 3G but I think it was misleading. Wiped and flashed to evodeck and it went back to showing 1x. My phone has 3G showing on evodeck next to his so he definitely has 3G coverage.
I guess it's just time to call Sprint for a re-provision? Does it have to be on a Sense ROM for them to reprovision?
Click to expand...
Click to collapse
you dont need Sprint to provision, just get your MSL code and do it your self plus I would do a search for people who may of had similar issues and see what they did. Now if that does not work then why dont you check what your network settings are.. See if its set to CDMA(Auto) I remember my Touch Pro I could of set it to 1x maybe something is getting stuck. I think its in ##3282 you check it and I also remember an app on the market called network that did it for you as well.
If that does not work then flash 3.70 radios and then a 3.70RUU and start from scratch.
He already tried ##data#. He can change his EVDO to automatic but it doesn't stay that way.
Alright I don't know how I fixed it but it's fixed.
Just cannot get 4G now. Wimax keys are present. It keeps scanning and cannot get connect. Previously could get 4G at these locations.
I am running EVO as donor/target phone, my is only 1x speed, no matter which rom I try
Synergery, Mik, Stock-Rooted, differ kernal, different PRL, check the data profile Automatic, Try restore but can not cat automatically update, still need to go qpst to update my profile. I have been working on this for two weeks. I went back to my orig phone, it show ev most of time, the speed is must faster than my evo. Searc all over from goole, still no luck, Anyone any idea to try
sitlet said:
I would try flashing the latest radios just to be sure. And tell your friend to always make a nandroid backup to avoid this problem in the future.
Click to expand...
Click to collapse
+1
i know this post is somewhat old. but Making a back up wont take hardly and extra time! always always make one unless you have 100% reliable roms already backed up.
Sprint Galaxy Nexus
4.2.1
Not rooted
I performed a factory reset on my phone yesterday due to it bogging down and being rather slow. I never did a reset after getting the 4.2.1 update so I figured it was a good time. I woke up this morning, putzed around the house, and setup Tasker again. I laid my phone down for ten minutes while I got ready for work. Whenever I tried to wake my phone and nothing happened. I tried a few more times and the screen would not wake up. I pulled the battery, hard reset, reinserted battery and the phone wouldn't turn on. Then, I wiped the contact terminals (on the battery and the phone) and reinserted the battery and the phone booted up. However, since then I have had some major problems.
1. Power button does not always work properly. I have to press it several times to sleep or wake the phone. (Okay, not major, just inconvenient and probably unrelated to the issues below)
2. No data connection whatsoever.
3. In the data usage menu, there is no longer a data toggle switch.
4. Under the Network Mode option, LTE/CDMA produces absolutely no cell signal whatsoever. I have to switch to CDMA only. (WiFi works fine)
5. Toggling airplane mode, as some have suggested, does not cause the phone to connect to mobile data. Another factory reset did not restore mobile data. Rebooting did not restore mobile data.
6. All of these problems are true before and after factory reset. No new problems were created and nothing was exacerbated as a result of performing a factory reset.
I've been from one end of the internet to another looking for solutions to this problem and I have found that many are having a similar issue but toggling airplane mode or rebooting fixes it. Not the case for me. Most also seem to be having this problem after rooting. Again, not the case for me.
Any suggestions? I would prefer to not return the phone. Purchased from Radioshack and the 30-day warranty has expired. This is my second gnex already, as the first one's charging port broke. It took over a week to get this one from another store which graciously shipped it in to my store. There's also the issue of being broke and not really being able to afford another $30 activation fee on top of the deductible for a new phone.
Why not try reflashing the stock image and updating again to 4.2.1?
Beauenheim said:
Why not try reflashing the stock image and updating again to 4.2.1?
Click to expand...
Click to collapse
Wouldn't I have to root first?
nburns1825 said:
Wouldn't I have to root first?
Click to expand...
Click to collapse
Not at all. You'd use Odin . Myself I have very spotty sprint signal in my home. Spoke to a corporate executive and they mailed me an AirRave free . Never have less then full bars 3g all around home. You should a- flash to stock using Odin following posts in sprint sextjon . b - call up and try to get an airavana.
Sent from my Galaxy Nexus using Tapatalk 2
n0ve said:
Not at all. You'd use Odin . Myself I have very spotty sprint signal in my home. Spoke to a corporate executive and they mailed me an AirRave free . Never have less then full bars 3g all around home. You should a- flash to stock using Odin following posts in sprint sextjon . b - call up and try to get an airavana.
Sent from my Galaxy Nexus using Tapatalk 2
Click to expand...
Click to collapse
Excellent. I will give it a shot at some point today or tomorrow and then let you know how it worked out. Thanks!
So, I restored the phone to stock. Signal is still non-existent on LTE/CDMA mode. Cannot perform Profile or PRL updates. Still no mobile data. I'm guessing hardware failure?
Also, on setup it asks for a SIM card. And at the bottom of the drop-down menu, it says "No SIM card|Sprint" or "No SIM card|No Service" depending on if I am in CDMA or LTE/CDMA.
Also, in the Status menu:
My phone number
Unknown
MIN
Unknown
PRL Version
Unknown
ICCID
Unknown
Seems a little odd to me.
Attempted fully rooting and flashing radios. No luck there either. It's also not wanting to update. Tells me my phone is up-to-date (connected via WiFi). Downloading Cyanogen now to see if it will work in the morning.
And while attempting to flash a new ROM, got the famous "can't copy anything to the device ever, under any circumstances" error.
Update: Got CM10 installed. Still "No SIM" error, no 3G, no data, no LTE. Found some more information on this No SIM error. Apparently a few others have had this same problem and in the end had to get a new phone.
Anyone know anything?
You should a- flash to stock using Odin following posts in sprint sextjon
I've been back to stock twice now. The first thing I did was flash to stock. Then I played around a bit and now I'm back to stock again.
Is there a difference between using Odin and Nexus Root Toolkit to return to stock?
Bump
Wow, one day and my thread is buried!
After battling for about a day, I got updated to JB 4.2.1, I can do profile and PRL updates again, but there is still no 3G/mobile data, and I still have zero bars on LTE/CDMA and have to use just CDMA. I am currently stock but the bootloader is unlocked, no root.
If anyone has heard any solution, please help. Also, if there's a difference between flashing to stock with Odin vs NRT, please say so.
nburns1825 said:
Wow, one day and my thread is buried!
After battling for about a day, I got updated to JB 4.2.1, I can do profile and PRL updates again, but there is still no 3G/mobile data, and I still have zero bars on LTE/CDMA and have to use just CDMA. I am currently stock but the bootloader is unlocked, no root.
If anyone has heard any solution, please help. Also, if there's a difference between flashing to stock with Odin vs NRT, please say so.
Click to expand...
Click to collapse
Try fastboot flashing your LTE and CDMA radios again. As far as I know, fastboot commands do NOT require root. I had a similar issue.
Edit: link to post with directions http://forum.xda-developers.com/showthread.php?p=39446679
Sent from my R2-D2 unit on the far side of the moon
Indeed, fastboot does not require root. I've flashed my radios several times now in various different ways. I even flashed different versions. I attempted again but with no luck. I have normal service when using CDMA but nothing on LTE/CDMA. Still no data, still "No SIM card" error.
Pretty sure I'll have to get it replaced. I've gone from stock JB back to stock ICS, rooted, CM10, back to stock ICS, rooted, back to stock JB unrooted, and flashed three different radios. I'm surprised I haven't managed to brick it yet.
UPDATE: Sprint is sending me a new phone, for free.
I've tried all sorts of roms, AOSP and Sense, they all stay connected to 4g for a few minutes at most after a reboot and then go back to 3g.
Everything else works fine, and my sim works good in other phones and stays on 4G.
Any idea what this could be or what is causing this?
Have you updated to the latest firmware? If your using kitkat roms, you need kitkat firmware. You can find the firmware in the second post of santods stock rom thread in development. Use the no boot.img one.
cmlusco said:
Have you updaTed to the latest firmware? If your using kitkat roms, you need kitkat firmware. You can find the firmware in the second post of santods stock rom thread in development. Use the no boot.img one.
Click to expand...
Click to collapse
Yea I've flashed those also. Everything used to work fine until that roaming display issue. Never returned to normal for me, even tho roaming is gone.
Have you ever ruu'd back to stock and then done a factory reset from hboot? That is the only way to wipe out the network settings and force them to be updated. Worth a try i guess.
cmlusco said:
Have you ever ruu'd back to stock and then done a factory reset from hboot? That is the only way to wipe out the network settings and force them to be updated. Worth a try i guess.
Click to expand...
Click to collapse
I guess that's my only option, thought maybe I'd be able to avoid it.
I'll try tomorrow and update.
Tried to ruu back to stock yesterday and still getting the same results. No 4g after a few minutes.
Sent from my HTC6500LVW using Tapatalk
Dethsesh said:
Tried to ruu back to stock yesterday and still getting the same results. No 4g after a few minutes.
Sent from my HTC6500LVW using Tapatalk
Click to expand...
Click to collapse
I'm not getting 4g at all on my phone. I came here to post a question and saw yours, so thought posting another thread would be pointless.
I've got NusenseSIX RC4.5 running and while the 4g icon comes on, there's no data transfer at all. I flashed the new firmware first, as instructed, and that seemed to go just fine according to the directions. But, when I swapped my sim card from my other One and waited a few minutes, even *228'ed, no data.
I got the phone already rooted and s-offed with TWRP 2.7.0.1. How do I get it back to stock to clear out the network settings? Or could it be a bad firmwware flash, so I'm screwed anyway?
EDIT: I redid everything, and just stuck with the Sense 5.5 mostly stock ROM. Data works now. Might've been firmware, might've been the ROM on my phone. Zero idea.
Is it possible to have a bad sim?
I just got a replacement device and I still cannot get 4G service for more than about 2 minutes before it switches to 3G
Souldrifter said:
I'm not getting 4g at all on my phone. I came here to post a question and saw yours, so thought posting another thread would be pointless.
I've got NusenseSIX RC4.5 running and while the 4g icon comes on, there's no data transfer at all. I flashed the new firmware first, as instructed, and that seemed to go just fine according to the directions. But, when I swapped my sim card from my other One and waited a few minutes, even *228'ed, no data.
I got the phone already rooted and s-offed with TWRP 2.7.0.1. How do I get it back to stock to clear out the network settings? Or could it be a bad firmwware flash, so I'm screwed anyway?
EDIT: I redid everything, and just stuck with the Sense 5.5 mostly stock ROM. Data works now. Might've been firmware, might've been the ROM on my phone. Zero idea.
Click to expand...
Click to collapse
Dethsesh said:
Is it possible to have a bad sim?
I just got a replacement device and I still cannot get 4G service for more than about 2 minutes before it switches to 3G
Click to expand...
Click to collapse
Sure, you can have a bad SIM, but I don't think that'd cause the drop in data transfer rate... lack of data all together, or other things not working, sure, but if you can actually catch a 4G link and then it drops to 3G, sounds more like the radios, the hardware, or just a bad coverage area. I'm no expert, though.
In case anyone was wondering, I ended up getting a new SIM and that has fixed my 4G issue. No idea what was wrong with the SIM, but anyway it sucked.