About two months ago this same question came up and was answered here:
That page links to the T-Mobile support page on HD Voice here:
But the problem is that page still only lists 3 phones that are supported: Samsung Galaxy S 3, HTC One S, and Nokia Astound.
There are many newer phones that are supposed to support HD Voice on T-Mobile: iPhone 5, Samsung Galaxy S 4, Samsung Galaxy Note II, Nokia Lumia 521, Blackberry Q10, Blackberry Z10, Sony Xperia Z
... yet those phones aren't listed on the HD Voice support page. So where can we actually find a reliable list of all the HD Voice capable phones?
Also, is there a difference in whether you get HD Voice if you bringing your own unlocked phone (assuming it's one of the supported models) versus buying it from T-mobile? I'd hate to bring my own unlocked phone only to find out that somehow that means I won't get HD Voice support.
Furthermore, the Google Nexus 4 hardware supports AMR-WB (the implementation of HD Voice that T-Mobile uses), but I can't find any evidence on the internet that this phone actually gets HD Voice on T-Mobile US. Is there a reason why it's not supported?
I'd love to switch to T-Mobile but they're making it hard for me to make 100% sure I get a device that will support HD Voice.