I have a pretty unique problem and im not sure there even is a solution, but here goes.
The story is that I had been living in Canada for the last 7 months or so and bought myself a shiny new Desire 601 from Virgin Mobile (its a zara_ul). Since then, I have managed to brick it hardcore style, but i was able to ressurect it after 4 months of fruitless attempts through various odd files, sheer dumb luck, and the RUU from mrplowdans google drive (super props by the way, you saved my phone good sir!). I had to SuperCID the phone in order for the RUU to stick.
So it goes without saying that im now running the Telus version of KK (i updated through the usual OTA once i had returned it to stock 4.2.2) on a VM phone. All good, no issues there. Ive since returned home to Australia, unlocked the phone so it works with an Australian carrier, also all good. Im able to make calls and send texts no issue.
My problem is with mobile data. It seems to be having an issue connecting to my carriers 3g/4g. Initially, there was nothing at all, just the bars in the notification bar telling me that i had a good connection to cellular. No little superscript 3G though, and in settings, although mobile data is 'On', it is showing connection failed. Adding a custom APN appeared to work slightly, the 3G appeared in the notification bar and in settings, mobile data was shown to be 'connected', but still no dice when i try to connect to the web or download an app.
Now i vaguely understand the principles involved here, I get that North american carriers use a different radio frequency to, say, Europe, and that differs again to Australia. My question is, is it on the software side? Would it be possible to find an Australian Radio.img for a desire 601 (i dont even know if they sell them here), flash it, and all will be fine and dandy? Or is it the physical antenna inside the phone that is set to receive only a certain frequency? Im not expecting someone to go and find me a working file or anything, i know most of you live in Canada anyway, but im looking for someone with a greater knowledge of these things to find a theoretical fix.
I know I rant a lot, but in the scheme of things im willing to let this problem slide considering i only just un-bricked it a few days ago AND managed to root 4.4.2 (a significant achievement given my non-existent knowledge of android), but it is a nuicance and if theres something simple i can do of course i will.
Thanks in advance for any help <3
EDIT: Ive since done some googling and discovered that they do sell these phones in Australia, and that the Network specs for it and the canadian model that i have are almost identical, many of the frequencies are the same on both. Leads me to assume that its software sided, the telus radio.img is telling the phone to not see non-canadian frequencies.