Phone problem or car

[UAxDEATH(NYC)]

Hi all,

Here is the usual problem that I'm having with my HTC ONE M7(and M8) Verizon and BMW X6M 2013. After each call, when I have finished conversation and clicked on the hang up. Its makes a huge NOISE to indicate that call is being finished. I have BMW Explorer, but I don't know where to look. Sounds aka Noise is like Big "DONG" sound, and its 10 times louder then actual voice on the phone. I have checked with other model of BMW, that sound still exist, still the same, but MUCH MUCH lower volume, you barely can hear it at all. Some version of BMW it doesn't exist at all. All models were tested 2013+. Different phones like Iphones, works just fine. So I'm looking for help. Please it drives me nuts, due to nature of my business and road travel, I have to spend 80% of my time in car driving and talking.

Thank you