FYI, the closer you get to the towers on Top of Nanum the spottier your signal can get. It has to do with different radio signals competing with each other. Also, the type and model of phone will have an impact on your reception. I have been up there with others who had the same service provider and one of us can get out and the other can’t.
Something else that is unusual up there. I have used a ground fault listening device that uses a microphone to amplify noises underground. You can pickup radio station broadcasts from the Yakima area up there by just placing the microphone on the rocks up there.