This is NASWAS that you were hearing if you were listening on the feed below. If you are not familiar with NASWAS is mostly telephone based, but there are a few emergency ops centers that broadcast it. (
National Warning System - Wikipedia, the free encyclopedia) In my feed listed below, I have 156.000 out of Grand Island programmed. It does have a very long squelch tail and consumes a lot of the feed during severe weather. During severe weather, you will hear National Weather Service out of Hastings, North Platte, and even sometime Cheyenne, WY reporting to local PSAPs regarding watches and warnings that are issued.
On a side note, they also run NAWAS role calls with all the states a couple times a day that are kind of interesting to hear. This would definitely be a good frequency to monitor during a major disaster.
Other known NAWAS rebroadcasts in Nebraska are 453.650 in Lincoln, and 155.745 out of Sarpy County (Omaha metro area).
No DTMF. My guess was this feed:
Broadcastify - Custer County Nebraska Live Audio Feeds
Again, it appeared to be PSAP to NWS, no idea what the daily use would have been. There are no matching descriptions in the RRDB that stood out.