Both my wife and daughter have this issue with their J7 refine. Problem seemed to start occurring about the same time on both phones so it may have been caused by a system update or something that changed on the network. Our daughter is 300 miles away so it does not appear to be a local tower issue. Randomly, usually within 24 hours, the phone will loose the ability to make or receive calls. Incoming calls go to voice mail directly. outgoing calls get stuck on Calling... If we power down and restart the phone the missed texts and call notifications will all stream in at once, but sometime within the next 24 hours it will not be able to make or receive calls or texts again. Signal strength is always good and this happens with or without wifi enabled. I have tried clearing the cache, resetting the PRL and even performing a factory reset of the phone. Our carrier is Virgin USA and they have not been able to help. From researching this issue it appears to be common with the Samsung J7 Refine but there does not appear to be a solution, or at least I have not run across it. Getting ready to drop my carrier and Samsung since I have been dealing with this same issue for over a year.
Same issue with Boost Mobile. Samsung will not own up to the issue. Since it is happening to another carrier, sounds like a Samsung issue not Virgin's. SamsungCole's (a Samsung Moderator), solution was this:
"Typically speaking with your carrier is recommended. Though I would recommend a software re-flash to reinstall the OS. You can check with your local uBreakiFix to have this completed, or Samsung offers a ship-in repair option. "
It is marked as the solution but is not. I asked the same back in September. The cost is 50 dollars, since it is not under warranty. Tried it and it did not solve the issue. Did the hard reset, at Boost and at home, it still wants to be updated, and again, same issue. There is no fix for this issue and I think there will never be. Samsung is pushing the higher end phones and could care less about budget ones.
I am having to buy 3 phones, 2 are being replaced with iphones, and mine, i have not decided if i will go with the A20 from Samsung, or another brand since they will not stand behind their budget products.