My Iphone 6 Plus keeps sporadically having this error. It doesn't allow me to have any data or service to use when this pop up occurs, it basically renders my phone useless. I have brought it into the Verizon store and they just reset my network settings. I've tried turning it off and on, switching to airplane mode and back, hard reset, update carrier settings. Just wondering if anyone has anyone had this issue and had it fixed? It may be as easy as switching out the sim card? Please help!