just a bit of info, the T-Mo model appears to be the same for Sprint and Verizon while the ATT model is different.
A1633 (6s): ATT (has the additional Band 30)
A1688 (6s): T-Mo, Sprint & Verizon
A1634 (6s Plus): ATT (has the additional Band 30)
A1687 (6s Plus): T-Mo, Sprint & Verizon
A1633 (6s): ATT (has the additional Band 30)
A1688 (6s): T-Mo, Sprint & Verizon
A1634 (6s Plus): ATT (has the additional Band 30)
A1687 (6s Plus): T-Mo, Sprint & Verizon