I recently switched to T-Mobile from VZW. I kept my Nexus 6 and so-far, everything seem mostly ok. Seems like there may be a few hand-off things going on, but nothing unmanageable But I don't have any of the Wifi calling options. I'm on LMY48M, but got that while I was on VZW. Do I have to flash an older T-Mobile specific image and then let it do it's OTAs? Or at this point, do i just wait for the Marshmallow release.