Problem is with a current Android 6 Lenovo.
With speakerphone button OFF:
No audio on dialing
No hearing other person talking
Remote person can hear me (mike working)
With speakerphone button ON:
Default install. Have PC with Win 10 in same room - works fine (no issue with dialing, connecting, blocked ports, etc. Have Android 4.4 phone - works fine.
(nothing seems to work)
to “External Java Driver” -- no improvement
Above 1+ed seems related.