For those reading and wondering what we are talking about:
ISPERN stands for Illinois State Police Emergency Radio Network. It operates on 155.4750, the nationwide Police Mutual Aid channel. While neighboring states also use this to some extent, IL has the most organized and frequent use of it in the Midwest.
By rule, ISPERN can be used for pursuits, certain flash messages and inter-agency coordination. Base stations are restricted to the various State Police posts and facilities, the Cook and Lake County sheriff offices and Chicago PD. Some trunked systems have full or port time links to ISPERN as well.
DuComm has established a full time simulcast of ISPERN on 470.4375, as has already been mentioned. Transmitting from a tall tower (I think it uses the Elmhurst site, but I am not sure...) it receives ISPERN from several satellite receivers and rebroadcasts it on the UHF freq. At this time there is no talk back from the UHF to ISPERN.
As also been mentioned here, there is no one I know of with a webcast of ISPERN, but it would be a great idea if they rebroadcast the UHF link, as it receives far and wide. I often hear Springfield and Rock Island when conditions are good via the DuComm system, just the other day I listened to some Iowa units near Des Moines.
DuComm also has a similar link to the 154.2650 IFERN (Interagency Fire Emergency Radio Network) on 470.3625. This allows one to monitor large incidents they would not otherwise be able to hear.
DuComm is one of the premier central dispatch agencies in the nation, and has been very generous to the scanner community over the years, with tours to local scanner clubs and publishing freqs on the Internet etc. While these links are intended for the professional use of the member agencies of DuComm, the side benefit to scanner listeners has been well appreciated.
