@rik AT&T. Hope to switch to another carrier soon. Interesting about texting on 4G. I just tried and it wasn't working at all, then I restarted the phone and it is working fine. I couldn't get it to send images earlier and now that is also working. I even texted some 60mb tiff files and it sent them no problem. It looks like I can both send and receive long lines of text and images with wifi on. I basically never text and not in 4G, so it's hard to make a comment about reliability, but it seems to work at the moment.
My 6T is also having this issue. After some time, I'm not able to receive/make calls receive/send SMS even mobile data remains enabled and teleports notifications coming in.
The reboot fixes, but after it repeats. I'm using the 2G/3G/4G option. Some other people are also having this issue. I've to send a sms myself to check if at that moment I'm able to receive calls. Since last RC update this became an everyday problem.