How To Use Secret Codes On Oppo A9 2020 //top\\ Official

*#*#42#*#*

Dial *#*#3646633#*#* → Audio → Normal Mode → Type: Sph. Increase the value from 100 to 130 (do not exceed 140 or you risk speaker damage). Reboot. Call volume improves dramatically. How to Use Secret Codes on OPPO A9 2020