First of all go to your phone's settings.
By Sohail Akhter
Image: Google
After that scroll down and go to Google tab.
Image: Google
Scroll down until you see the Settings option for Google apps.
Image: Google
Then tap on Search, Assistant and Voice option.
Image: Google
Then go to the Google Assistant tab
Image: Google
Now scroll down and tap on Assistant Voice & Sounds option, which will be available under All Settings tab.
Image: Google
In this, you get red and orange labels indicating female voice and male voice respectively.
Image: Google
Now tap on the orange circle to activate Voice Mail for your Android device.
Image: Google