What do you need?1. Download MediaTek SP Flash Tool v5.13.52.2002. Download Android KitKat firmware.What do you have to do?Take a look at the below video and follow these steps:1) Unzip SP tool and firmware2) In SP tool folder, locate and run Flash tool.exe3) On Flash Tool, under the 'Download' tab, Click on "Scattering Loading" and select the scatter file (txt) in the firmware folder4) Once selected, the respective "Download Agent" and "Scattering Loading" files will be loaded onto the SP tool5) On Flash Tool, click on the "Option" tab and look fora) "Connection and select High Speed Option b) "Download" and select "DA DL ALL with CheckSum"6) In Flash Tool, under the Download tab, click on the drop down button and change "Download Only" to "Firmware upgrade"7) Turn off your phone, take out the sim card, TF card and battery. Do not put back anything.8) On Flash Tool, under the Download tab, click on the Green colour "Download" button 9) Connect your phone to the usb cable.10) You will see a red progress bar at the bottom. Once done, a Green colour Circle will appear and YOU ARE DONE!If you want root, this method is still working just fine. (already tested by me)It's true, now the low volume in voice calls is gone, everything is working just fine. (also tested by me ;) )