As all we know the WCDMA 800/850/900/1900/2100 Mhz is only a mirage, because we all know that the in example the JIAYU G4T is supporting ONLY WCDMA-IMT-2000 (which is the WCDMA 2100Mhz).
OK from my experience so far, I have flashed so many modem.img files, from TCL Idol X (S950), TCL Hero N3 and ChangHong Z9(HonPhone W33) and with no success, I'm only killing my reception because I SUPPOSE that the build of this stupit modem.img file is different or the JIAYU G4 BandMode is somekind of hardware locked only on WCDMA 2100, BUT WHY ???? Is there any posibility to unlock the WCDMA-GSM-900 Mhz, it is natively supported by the MT6589T and how the rest of the Manufacturers are able to implement it and to make it working ?
You'll ask your self, "why this guy is still trying by killing his phone so many times", well the answer is very simple, because I belive that there are no imposible things in the world and because I know how to recover my IMEIs and so on and I have even tried with the ChangHong Z9(HonPhone W33) Modem Database and AP Database and guess ... I was able to recover the IMEI and even I've used a real ChangHong Z9 IMEI and I was able to write it on my JIAYU G4T BUT ....
AGAIN with no success, there were no reception at all and I was having IMEIs and YES in the Engineer Mode in the Band Mode section there were only WCDMA-GSM-900 and WCDMA-IMT-2000 marked but there was NO reception again !!!
and that's why I'm begging you to tell me how to edit the modem.img file, because I was unable to uncompress it anyhow (tried ext4_unpacker_exe but without success, it's unpacking only mediatek factory rom ".img" files)
You'll ask why I want to edit and to try to create custom modem.img to support WCDMA-GSM-900Mhz, because those idiots from JIAYU and not only them, are going to release their MTK6592 and even the other upcoming 6595 with only WCDMA 2100Mhz support and that's very STUPID !!! And at all JIAYU have a great design !!!
Only in Europe there are 45 x Mobile Carriers with WCDMA(UMTS) 900/2100 Mhz builded networks (Including big mobile carriers like O2 in UK) and all of us which are using JIAYU or THL or even almost all of the rest chinesse clones or other manufacturers MTK based phones, we all are going to suffer if we are in such area which is WCDMA 900 coverage available only.'
I'll give you an example which is very clean example for good marketing: TCL
they have 4-5 different Idol X S950 modem.img files for their 4-5 different versions of the Idol X S950 model !!! YES I was able to check that fact by accidentally founding the source codes of the 4-5 different region specific TCL Idol X S950 phone and after that I was able to read that for every region there is different modem.img which is region specific in the needs of the customers mobile carriers.
You'll ask me "Why don't you buy Idol X" because the JIAYU is smaller it fits in my hand better, that's why and because I like the design more and because have an OTA updatable MIUI V5 on it which is working flawlessly, that's why.
Also why I'm going to buy the next MTK6592 based JIAYU S2, because it have even better design (139mm x 67.5mm x 6mm) than the Idol X+ S960T (140.4 x 69.1 x 7.9 mm), but again it will strugles in WCDMA 900 Mhz that's why I beg all of you developers to help me to figure how to redifine the modem.img to be custom configured by our needs ?
Thanks in advance and sorry for the long post