Unit 15 has intermittent coverage with US Cellular (GSM) or Verizon (CDMA), so should have some roaming coverage at the very least.
On the East side of 15 I was able to have cell service on top of a peak I hiked to. On the west side of 15 I wasn't able to get any cell service. I have sprint for a carrier. Don't plan on service but you might get lucky.