HD voice

[kevm14]

Lumia 521 does not support it. http://support.t-mobile.com/community/p ... _lumia_521

HTC 8X does not support it. http://support.t-mobile.com/community/p ... _8x_by_htc

So the better clarity I heard I would put down to the 521 itself, or possibly that T-Mobile has a little better bandwidth on their regular calls, but I doubt that.

Info on HD voice: http://support.t-mobile.com/docs/DOC-5407

This claims the 520 supports it: http://en.wikipedia.org/wiki/List_of_Sm ... g_HD_Voice

Current HD voice is on HSPA I guess but VoLTE (which isn't necessarily synonymous with HD voice) is planned for everyone basically: http://z6mag.com/technology/volte-and-h ... 16198.html