THL W3 with v4.0.4 - periodically getting "Restricted Access Changed" and losing all SIM services What happens exactly: when I use my SIM's data connection, after 1-5 minutes of operation (be it while the phone is active or locked), I get a notification "Restricted Access Changed", losing all SIM services -- voice and data. And I get prompted for my PIN. This only happens when I use the SIM's data connection. Using my home router's Wi-fi never introduces this problem.

I had this out of the blue since several weeks ago. I didn't drop or hurt my phone in any way.

I tried using SIM cards of 2 of my friends on my phone. They never had problems on their phones (their Android versions are more recent than mine, just pointing that out). Again, after 1-5 mins of idle/active operation on my phone, we get presented with the same error message and PIN input dialog.

I tried these:


Reset to factory settings -- no apps, nothing. Only started Play Store and locked the phone. Just a minute later, boom, the same problem.
Removed my SD card. No change.
Tried putting the SIM more firmly in the slot (used some paper to make it fit tighter). No change. Though, I only tried that once and not very stubbornly. I guess I'll try that again in the meantime.
In my mobile network, I only have the options of "GSM / WCDMA (auto)" and "WCDMA only". Using either of both doesn't change anything.
Switching off 3G seems to "fix" this, which is of course no fix at all since the network gets at least 3 times slower. Not to mention I can't view any video, etc. I can't count that as a solution.


Here are few links from my google hunt:


Restricted access changed (XDA-Developers)
Unlocked Chinese Android/Restricted Access Changed (Howard Forums)
"Restricted access changed" + "Voice call service blocked" (XDA-Developers)
Restricted access changed (XDA-Developers)
HTC One S is showing, Restricted access changed. Data service is blocked (XDA-Developers)


Some thoughts:


I didn't manually install new applications by the time the problem started occuring.
As said, I didn't drop or hurt the phone in any way.
My data plan is having a limit of 1.5GB. I rarely go over 500MB, and the last month was no exception (I am regularly checking the used bandwidth and traffic on the phone).
The phone is rooted. I am periodically getting BusyBox updates -- I suspect that might be the culprit since it updates a plethora of system files. But I admit that I am no expert in rooting and/or flashing Android phones, and the last sentence might have been an extremely nooby statement. Sorry if that's the case.
The problem is consistent: with 3G enabled and only using internet from my SIM (again, not through Wi-fi, the problem is not present there). However, there's no fixed period. It varies between 1 and 5 minutes, even though I had 2-3 cases where it worked properly for ~15 mins. I am suspecting that the moment the phone's networking hardware/software goes over a certain load, the problem occurs.


Steps I didn't try:


Flash a new ROM. Thing is, THL don't have more recent ROMs than the one I got the phone with when buying it off a friend. He downloaded the latest image from THL's website and flashed it, then rooted it. We never tried using unofficial ROMs.
Flash only the radio software. (I don't have an idea how this could be done, though.)
Call my mobile provider to ask if my IMEI is blacklisted. Or if they have a malfunctioning cell in the area. (Still though, that can't explain why the problem does occur 6km away in a park as well, so I don't think a malfunctioning tower/cell is to be blamed).
Go to repair shop for diagnostic/repair of the internal antenna. I would like to leave that as a last resort. From what I hear, this could easily cost $100. And that phone costed me $200. If I have to do this, I might just go and buy a brand new Galaxy S4 as well. Still, I don't want to just throw it away. Obviously, even if I replace it, I'd like to be able to sell it and not burn the guy I sell it to.


I am out of ideas now. Even though I am by no means an Android expert, I have tried quite a few possible solutions without any effect so far.

Can somebody help with this, please?
I had similar problem with my brand new Snopow M6 phone. And I'm sure, that this may be common to most Chinese Android phones. First, in Estonia we have 3 major mobile operators, and with SIM cards two of them my phone worked nicely, it did not work with my own SIM. Also tried almost everything, but then started check IMEI code through the operators' networks. And found out, that my operator follows the idea, that its not good enough just not to be in their blacklist, You have to be in their white list. So I gave them a call, and they manually added my phones IMEI to their white list and phone works flawlessly since then. So, if you buy a Chinese phone from the Internet, then first check Your IMEI through carrier, random internet sites might give You an answer, that phone is not blacklisted, but that might not be enough in some cases.