Simple answer is no.
I have been on Junipero Serra, and on parts of the coast ridge, Ventana double cone trail, with clear line of sight but with no luck. Many of the new phones, they can't handle when you get multiple access to receivers. It seems that when the receivers are at great distance, even though you can see them on a mountain many miles away, doesn't mean you will get reception.
Even more frustrating is that about 10 years ago I had a somewhat larger ATT phone, it got great reception at many locations in the wilderness where I get no reception now, and I don't know why.
