Viber mic volume is too low topic

I am wondering if anyone using viber and facing this issue or not.

currently when trying to make\ receive calls on viber, the other side complains that the volume is too low

I had tested this against also my Galaxy S5, the fire phone still have very low mic volume, so I can barely hear.

I suspect the problem might be that Viber is picking the wrong mic (if fire have multiple mics), or just gain issue.

Smart call viber? topic

So Sony has this feature called smart called where if you activate it and then if someone calls you, you just out your phone to your ear and it automatically answers the fall without swiping the phone to answer. So I was wondering if this could be implanted to work on viber? Because it only seems to work if someone calls you via the regular phone, apps like Skype, viber etc can't use this feature

The application of Viber realtime notification problem topic

Viber messaging program is installed on my phone.

But I can not get real-time messages Viber.. Other programs are able to instant message notification but I can not see when I open the Viber app new posts.. I would like to receive instant messages.
What could be the problem with this?

phone model: ZTE Redbull V5 V9180
Thank you so much!