Some users reported, compared with other models, it seemed there is a low in-call volume problem on ZenFone 6. In fact, for its all-screen display, the receiver on ZenFone 6 is in a higher position than it is used to be. Therefore, we recommend you to adjust the position as demonstrated below to hear clearly when answering the calls.
▲ Receiver position on ZenFone 6
▲ Please make sure the volume output is not blocked when holding your phone.