I was at the Portal a couple of weeks ago, and got service there. I have Verizon and an S4 phone. If you ask Earline the best place to stand for service, she will point you to the best rock!
Also - I've found service on the summit to be a bit spotty with Verizon. I suspect it depends somewhat on the model phone itself, how many people are attempting to connect, and a bit of luck.
I've had reasonably good luck when I'm in one of the windows between the summit and the jct to Guitar Lake. Something about the signal getting concentrated between the rock slabs? Dunno, but it has worked in the past for me.
