There could be a way in the future with some modification, I read the other day that AT&T and Tmobile are testing VoLTE (Voice Over LTE). Sounds like the ATT could be out sooner than Tmobile. Maybe we will get something at the end of the year.
Inspire 4g 6/2011 - 5/2011 R.I.P
S4 - Rooted MK2, MDL Firmware
Nexus 7 Stock Rooted