I have gone to the store and called customer service. Neither have been able to help.
We just switched from Verizon to T-mobile due to much better plans for the same price. I am seriously second guessing that decision now.
When my wife and I talk to each other on our Galaxy S7's, there is a hissing notice. Words sound very compressed. Like a terrible internet call. S's get slurred at the end of words. Noises in the background sound bad too. If I talk to someone on another network, the sound is perfectly clear. If I call a landline, the sound is great too. If I call my daughter's J7, the hissing is back. But if my two daughters call each other on J7's, they are clear. In short, it is only when an S7 is on one side of the call and the call is with another T mobile user.
Here is what I have tried to do to fix it without success:
1) turned off wi-fi calling. Turned on wi-fi calling. The problem is the same for both.
2) called from different locations - the problem persists no matter where we are on the network.
3) turned of LTE calling - the problem persists.
I has a suspicion that they have turned up the fidelity on the HD calling so much that it causes the S7 to hiss when trying to output the high treble. But customer service said there is no way to turn off HD calling. This seems to be true, because it says HD calling no matter if LTE calling, wi-fi, or other settings are changed.
Is it possible both S7's are defective? What else can I try?