I'm far from certain but the following quote from
http://www.apco911.org/frequency/siec/documents/alaska.pdf may answer the question:
Deployable Systems
In support of widespread VHF use by responders in Alaska, both federal and state agencies are
employing VHF deployable trunk and conventional capabilities. These transportable systems
consisting of a base station and repeater equipment, trunked and conventional, will be staged at
central locations for response to emergencies. Conventional systems will use frequencies
adopted for nationwide interoperability (Appendix E). These conventional VHF frequencies are
programmed into the user radios to provide interoperability when beyond the coverage area of
the trunking system, both inside and outside of Alaska. These same transportable systems will
also maintain a cache of subscriber equipment to supplement deployed agencies that do not carry
P25/TIA-102A VHF trunked radio capabilities. Further, agencies operating 700 or 800 MHz
infrastructure are highly encouraged to maintain a cache of VHF P25/TIA-102A trunk radio
subscriber equipment to facilitate mutual aid and response outside of their home infrastructure
coverage. Alaska first responders who expect to engage operations outside of Alaska, such as
the fire service should then ensure that they have a communications capability compatible with
systems in other areas of the country.