Marine Corps Museum Using 900 MHz ISM?

The National Museum of the Marine Corps may be using 900 MHz ISM radios for security. I wasn't able to get a good look at the radios, but one of them appeared to be a Motorola DTR-series portable. These digital radios operate license-free using frequency-hopping spread spectrum (FHSS) technology. They are not encrypted, but scanners are not able to monitor them. The DTR radios are intended for on-site use; they operate as simplex only.