[Q] Unlocked xperia Z1 network locked because of flashing Branded Firmware

i have a Sony Xperia Z1. the model number is C6906. i bought it directly from Sony and its Unlocked . it was working on every sim card. But i flashed the C6906 firmware of the other branded network provider. now it's network locked with that network provider. it only works with the sim card of that network. when i put any other sim card, the dialog box appears and it tells to insert network unlock code. when i contact that network, they told me to get their sim card and use it for 90 days. then they will provide me the unlock code. why should i have to use their sim card for 90 days to get the unlock code, because my phone is already factory unlocked from sony. i went to 3rd party websites which provide network unlock codes. but they didn't find the unlock code for my phone, because that phone is not present in the database of that network provider. that means i can only get the unlock code from that network code by using their sim card for 90 days. but that network is not working in my area. please suggest how can i make it unlock again as it was before ? i will be very thankful

gregbradley said:

flashing FTF files will not affect the SIM lock status of a phone.

It will neither lock an unlocked one nor will it unlock a locked one.

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i flashed the firmware of Rogers for my unlocked xperia z1 C6906, which was Branded Firmware. my phone was working fine with all sim cards. but few days ago i put the sim card of rogers, the phone automatically restart and also install some rogers network apps in phone menu. after that when i put other sim card, the network unlock code dialogue box appears. it means that phone got locked with rogers now. the rogers technicians said me if you flashed rogers branded firmware, then if you ever put rogers sim card in it, then device will locked to rogers even if its unlocked from sony.

gregbradley said:

well, not sure how that works as its the first time I ever heard that happening. Not that I don't trust operators but I often find they do not know what they are talking about when it comes to the kind of things we do here at XDA

But, if what you say is true, flashing another FTF will NOT help.

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is there any solution ?

gregbradley said:

you already said it in your first post.

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can xda developers develop any software for that ? so that the network unlock code dialog box disappear and phone reset with original factory unlock setting