Several, maybe many, shortlines are using cell phones to either replace or supplement radios. And more and more employees are taking their personal phones to work, requiring the railroads to determine when and where they can use them, especially from a safety standpoint. I have a friend who is an Amtrak engineer, and he occasionally answers from the engine cab.
I have driven many times from Chama to Antonito with my cell phone, and it looks as if there is coverage from Chama to around Apache crossing, although it gets pretty weak around Cumbres. On the east end from the road I get no signal until I'm almost into Antonito.