I'm a bit confused by the call quality. I'm calling OnePlus users, Pocophone users, Huawei and Xiaomi Mi 9 users.
When calling them while they drive and have it connected to the car, everything is okay. They are all loud and clear.
When calling "normal", I can easily hear the Pocophone user as well as the Huawei user. If there's a call by a Oneplus 6, it's almost too quiet. Xiaomi Mi 9 is almost silent, it's a pain to understand the caller even with maximum volume.
The Xiaomi users are reporting a bit of crackling sound from time to time when I'm speaking, for the rest it's a very great quality.