Good grief -- finally thanks to the service menu (*#0011#) I can make calls again on my Galaxy S4. A bad flash took out my NVRam settings and I had to reset the NVRAM and then found the CDMA frequency was set incorrectly. After changing it from 30600 (?!) to 1900 I was able to receive and place calls again. Data, LTE, GPS are all working so hopefully I'm in the clear.