Dear blackview_admin,
The last update to version 20171011-0929 doesn't solve the issue during phone calls.

I only have the problem with bluetooth during phone calls. I can listen to music on the same device without connection lost.

The issue only happens during phone calls. And than after 30sek up to 4 Minutes.

Sometimes I get a massage from my Bluetooth device (Ford hands free kit) which says that there was a Bluetooth communication error and sometimes I can't hear the people talking but the Bluetooth device is still connected. After 15-20sek the Bluetooth connection is reestablished and the connection is stable for the next 30sek -4 minutes.

good information