Chosen Solution
Hello, i can not here when I receive a call but when called via WhatsApp it’s fine..
First thing I’d suggest is trying a different SIM card. If issue still persists with a different SIM on an iPhone 6 I’d think about a baseband issue, that’s relatively common when the phone has been dropped or flexed. Try also dialling *#06# on your numeric pad, in case you don’t get the IMEI number in return the baseband failure would be confirmed. That would be a board failure needing a Pro to get fixed.