Help How to increase the call value?

[deepaksuri82]

Could any one of you please let me know the bellow queries:

1. How to increase the call volume in micromax A 87
I had bought Ninja 3 before 6 months, now I am facing low call volume problem and especially very less call volume in outdoor e.g. traffic and crowd places. Kindly give me suggestion to increase call volume.

Thanks in advance