Similar Problem
I have an lg vs980 and I was using it with H2O wireless and later I changed to Simple Mobile. I'm living in Puerto Rico. The phone was working all right and, suddenly, one day it was always displaying 'emergency calls only'.
I did factory reset, then I reflashed stock lollipop and it was like nothing happened, keeps displaying 'emergency calls only'.
Then I found this post
http://forum.xda-developers.com/show....php?t=2394689 and applied the patch but didn't seem to resolve the problem.
As a last resort I tried flashing cm 12.1 and before first boot applied the patch from the cited thread but no result, keeps displaying 'emergency calls only'.
Has anyone found a solution to this problem?