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Help SIM Card/Wifi problems


Jul 1, 2013
Hi all,

I have a i9300 phone and it has worked all over the world flawlessly. On arriving in Cuba and inserting a Cubacel SIM card in the phone I noticed that the phones wifi stopped working. Inserting another countries SIM and resetting the phone will bring back the wifi.
I found some guys who do all kinds of stuff to the phones and they say it's a common problem here in Cuba. Not only with Samsung phones but with allmost all androids. Apparently some setting on the Cubacel SIM overrides the phones wifi settings causing the wifi to behave wrongly.
After inserting the SIM the wifi will loose contact with any wifi and when scanning for new networks it will only scan for a hundred of a second before giving up and not finding anything.
The guys I mentioned earlier have a solution that works by patching the phone. The problem is that you will loose said patch with every upgrade and I'm in no mood to pay 20$ every time an update to JB comes out to some smart ass who does not want to share the solution with me.

Can any of you folks wrap your head around this problem and give me hints on where to look for a solution? This isn't the normal power saving mode problem, it is 100% related to the SIM card.

My phone is rooted so I can change files and do what needs to be done to the system.

Best wishes,
Thats a strange one man. What if you use custom roms so you have no need for the official updates, would the patch work with a custom rom and would you still lose the patch when you flash a new updated version of the rom?

Hi Funkylogik,

Thanks for investing your time in this problem.

I've tried custom roms and the phone still loses wifi after inserting the SIM.

I don't know if the patch is firmware specific. I did pay 20$ once to get the phone fixed and when I got it back the phone had all it's data and apps left so it does not seem that patching it requires a factory reset or flashing it with a new ROM.
But I know I need to re-patch it when i flash it. Flashed it yesterday and now I got no wifi again.
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Man thats a bummer. What if you just take out the sim when you need wifi?
I wonder what it is about the sim that disables it.. is it still disabled in flight/aeroplane mode?

As soon as I insert the SIM wifi dies, does not matter if I remove it or use the phone in flight mode. To make it work I need to insert another SIM and reset the phone.

I've now tried three different SIMs from Cubacel on two S3 Galaxy and on one Galaxy Mini with the same result. I'm going crazy here.
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Dont blame you man. Do u speak spanish or whatever they speak in Cuba? Best thing would be to find out how these guys are doing it (in a cuban forum or something) and save yourself some money ;)

Yeah, think I'll have to bribe those guys to tell me.

There are no Cuban forums or such. Considering Cuba is one of the least connected countries in the world I was happy to find two people commenting on the SIM card issue. Both selling the solution
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I finally found out what was wrong. The SIM has a faulty country code that messes up my phones wifi. Easy to fix once you find the solution.


I installed the app, turned off wifi power saving mode in *#0011#/advanced on my Samsung Galaxy s3 and after that never had the same problem again.

Hope this helps someone!
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