Volume not working while on call with headphone connected

[AsusYouzr]

Please tell us some basic information before asking for help:
Model Name:601
Firmware Version:087
Rooted or not:not
Frequency of Occurrence: always
APP Name & APP Version (If your issue relates to the app): Phone app
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
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While headphone is connected ....
If i do a call or receive a call..
My phone's volume isn't working at all..
Means no change to volume when i press volume up or volume down buttons...
I can't low call volume or high call volume when headphone plugged on a call.

[victor010]

Hi there, kindly follow the below steps:
Check with other headphones/ earphones and see if the issue persists
check the headphones on another device and see if the issue is with the headphone.
Clear system cache.
Try the same under safe mode:
Hold the power button for 5 seconds => When the screen flashes with option => Press & hold power option => You will get an option to restart in safe mode
5. If still you face the issue factory reset your phone after taking a full backup : https://www.asus.com/support/FAQ/1006346/
6. Last option would be to visit the service center to have a check. Locate here: https://www.asus.com/in/support/Service-Center/India