How to change the pitch of the white-noise ***when placing a call*** with Samsung S10e connected to the Bose QC35ii?

Background

*Ok, here goes: Huawei P10 is still the best phone out there. (Only thing I miss here is an additional wide-angle lens, but hey.) After having taking it's ten-thousandst fall the glass splintered slightly on the side and the camera is showing focus issues (which can only be "fixed" temporarily by letting it drop on a flat surface: google it...) I decided I need to look for a replacement :( Regarding modern phones, I can't stand a notch, with the exception of the punch-hole on the side, like featured in the Samsung S10e. Thanks to Trump and the Huawei-Google-sanctions, the obvious Huawei P40 family is also out of the question.* ------

The Problem

Hitherto, I'd use the P10 in combination with a Bluetooth-connected Bose QC35ii headset for business **calls**. Sure, there was a distinct white-noise hiss already then when initiating calls, **but now this hiss with the S10e has a different pitch** and it's driving me bonkers / bananas. Note: 1. All devices have the **latest firmware and updates installed** (as per **20 Apr 2020**). 2. **No** (white-noise) hiss is present when placing a call [with another, USB-C wired headset](https://android.stackexchange.com/questions/201134/work-around-to-get-usb-c-headset-to-work-for-calls-in-android-smartphones) **or** *without* a headset. 3. The hiss **starts already when dialling and continues throughout the call**. 4. Listening to **music** does **not** cause any (discernible) white-noise (irrespective of whether noise-cancelling is on or off). Does anyone have an idea of how to change the pitch of the white-noise ***when placing a call*** with the Samsung S10e through the Bose QC35ii? ----

Related Link(s)

https://community.bose.com/t5/Around-On-Ear-Headphones/Bose-QC-35-Firmware-4-5-2-Noise-Cancellation-Investigation/td-p/285738 (interesting read, albeit not that helpful... doesn't cover a way to turn off the "hiss")