I have had this problem. I exchanged a phone with Verizon. The hearing aid work around didn't work for me. The work around that did work was to switch to speakerphone and then back to either a Bluetooth (car) or just as a handheld. I do like the phone but couldn't live with the clumsy switching back and forth, especially while driving so I returned the phone and will patiently wait for a fix and try again.
Dan
Dan