My voice breaks up during call - receiver cannot hear me clearly

During calls on my Huawei Mate 10 pro, my voice becomes difficult to hear clearly after a short time.

Meanwhile I hear the voice of the other person clearly for the duration of the call leading me to beleave that the connection is not at fault. Also when I make the call from the same location with another phone (eg. Samsung or Iphone), the problem is not present.

Different people have told me after variable duration of a call that they are unable to hear me clearly stating that my voice breaks up like a very bad skype quality conversation. It seems to become worse after a short time of the call.

I had the phone in for repair - no faults found. The phone was just reset to see if that would improve the situation. It did not - my dad quickly recognized that I had my Huawei back (and repeated that I should throw it away).

I found this discussion (https://forum.xda-developers.com/mate-10...) interesting - about how speech processing algorithm apparently has a problem with male voices - higher pitched voices should not create the same problem. I would really like to find a solution or at least an explanation for this problem.

I hope some of you might have some insight on this issue :-)