After the recent T-Mobile OTA update on my Samsung Galaxy S6 edge (64GB), I have begun having issues with receiving calls, that I have figured out to be somehow related to LTE and WiFi.
After the update, whenever I would disconnect from Wifi, my phone would only show a 4G symbol. Initially I didn't think much of it, but then I check under Mobile networks, and it was set to WCDMA/GSM. So I changed it to LTE/WCDMA/GSM. As expected, I started getting the 4G-LTE symbol and my internet speed went up as well. But this is where the problem started with my calls. The phone works fine until you connect to a wifi, and that's when the calls stop coming. I would have people calling me, some would get my voicemail, others, there would be no ringing at all. This happened for a few days, and I restarted my phone over and over and the problem would go away temporarily, but when I would connect to LTE and then go on Wifi again, the problem would start all over again.
So the short term solution is, if you don't want to miss any calls switch your phone to WCDMA/GSM, and it will solve the no call issue. However, this is only a temporary solution. I got the S6 edge as an LTE phone and I should not have to worry about having to switch back and forth and restarting my phone.
I have, twice, done a hard reset on my phone, but that has not solved the problem!
I have read on other websites that other people are having similar issues after the update. https://www.reddit.com/r/tmobile/comments/3am71v/s6_no_longer_connecting_via_lte_after_511/
If anyone else is having similar issues please post here so we can make T-Mobile aware of this issue, or if you have found a solution, please let me know. I love T-Mobile plans and it's service, I would expect that you guys would get to the bottom of this ASAP and find a fix.