wifi calling in Pixel 4a 5g, I can't hear

I have Pixel 4a 5G and am having exactly the same issues. When I am calling someone they can hear me, but I can't hear them. If I am calling 611 I can see that call started, but I can't hear even TMobile greetings. I have called TMobile multiple times on this and they tried to replace SIM card, to set LTE as preferred network instead of 5G, eventually even replaced my phone, nothing helps. The only thing helps is turning off WiFi (at lest it helped couple times) but that is not an option. Most of the time I have to reboot the phone to fix it. This is becoming really frustrating, because I am missing important calls, I can't rely on this phone anymore. Considering to go back to my Pixel 2XL (which has newer ever had any such issues). TMobile/Google have to fix their stuff.

send reports to Google if you want it fixed.  Carriers have little control on software unlike popular opinion.  Quite a handful of times OEM's have admitted this, but always flies under the radar with people.

I'm having the same issue with my 4a5g. I've had it less than two weeks and it's really annoying. Only Sunday to work when I restart it.

Got the same issue on Pixel 4a 5g. I got my phone 10 days ago, initially seemed fine, now can't hear anything when I make a call, and no one can hear me. Tried turning off wireless calling, no benefit - but I am also noticing that my 5g signal is at zero or just above, and often it says LTE instead of 5g. I just called the cell phone from a land line, didn't ring, went straight to message, then after I leave a message I get a pop-up message. So phone function is reduced to that of an answering machine. 

There a Google ticket for this? Still occuring to me even after factory reset.

Same issue here. pixel 4a 5g.  Following

I'm trying to enable WiFi calling on the same device - a Google Pixel 4a 5G direct from Google. I've been told by T-Mobile support that I CAN'T do that because of a firmware incompatibility. I would have had to have bought the device from T-Mobile. The "Enable WiFi Calling" checkbox is gone.

Do I understand that others here have this phone with WiFi calling enabled?

Same issue on my Samsung Note10+ 5G.

I'm having the same issue, with a pixel 3 and 5 on Wifi.  In contrast to others' experience I find that turning off wifi mid-call is sufficient to get the audio from the other side back.  No device restart is needed. 

same issue Pixel 5 - wifi calling outbound works, inbound answers call with no audio - turning wifi off in the call is enough to get the audio working