[ghaff]

I think that's fairly common in a lot of the bigger and more remote national parks. Death Valley has decent cell reception at Furnace Creek (the main visitor center and lodging area) but AFAIK there's none in the rest of the 3,000 square miles.

[blackflame7000]

Death Valley is also in a valley surrounded by tall mountains loaded with cell tower equipment so the signal propagates pretty easily because there are minimal line-of-sight obstructions.

[ghaff]

I can't say I've ever noticed cell phone reception outside of the immediate Furnace Creek area but it's possible you can pick something up from whatever is up on the mountains in some locations.

[robohoe]

Last time I was in Death Valley in December I could barely get any signal outside of Furnace Creek. Even in FC it was terrible. I had two cellphones on T-Mobile and AT&T for that matter.