More details under Communities. It appears that California is still deciding according to this report in State Scoop:
Communication has been critical to the evaluation process in California, where SPOC Patrick Mallon said the state “owed it to public safety” to share as much information as it could. Mallon reported that the state held 12 outreach meetings across the state attended by nearly 800 people and that they gathered more than 700 comments. More than half, Mallon said, were related to concerns about network coverage.
“The major concern was coverage,” Mallon said. “AT&T has really stressed their capacity, but capacity does not equal coverage. There’s a lot of areas in California where AT&T does not have good coverage. Agencies that provide services in those areas expressed the concern that if FirstNet is not going to provide any coverage then there’s no reason for us to subscribe.”