I live on the west side of Los Angeles and none of the three carriers can get me more than 1 bar of degraded (e.g., LTE) service in my home or on the grounds. It's a fluke of topography (I only get a couple of FM stations and no OTA television). I'm ~3 minutes from the 10 and 405 freeways. It's very possible in the mountains there's no service, 1 hour from LA.