In call volume root modify
This approach achieves desired functionality by communicating with Android APIs at AIDL level making use of ADB



Run the command:

adb shell service call audio 7 i32 3 i32 0 i32 1


Here, the service call refers to IAudioService. Click here  for more info.


7 is the function named setStreamVolume. It is the 7th in the list of functions in the interface IAudioService. Verify it here. (setStreamVolume takes 3 parameters streamType, index, flag)
i32 is to write the integer INT into the send parcel. (Alternatively we can make use of s16 for UTF-16 string)
3 is streamTypevalue. (Value 1 &rarr; phone, 3 &rarr; speaker, 4 &rarr; alarm, 6 &rarr; bluetooth)
0 is index value and 1 is flag value 


See the source here.