I moved from Joplin a few months ago. I didn't realize that the system had that many talkgroups. In regards to some of the questions asked, this might be useful.
1. The guy that maintains the trunked system told me back in 2003 that Joplin would eventually go digital with an APCO-25 system. One of the big challenges now is how the Joplin and Springfield Fire Departments can communicate with each other and local fire departments since both departments play a role in regional homeland security. Ironically, the county 911 does not seem to want to go trunked at this time. Lack of money for volunteer fire departments probably plays a big role in this decision.
2. The Missouri APCO representative told me at a SEMA (State Emergency Management Agency) conference that the MHP was seriously considering going to a 400 Mhz trunked system since higher frequencies would require many more towers. I'd heard that St. Louis programmed their system a few years back for 700Mhz, but everyone is still waiting to see what comes of these frequencies. Even though lowband seems to work fine for the HP, interoperatability is the big word in communications right now.
3. When I did monitor Joplin's system, I noticed that the control frequency often changed on one of the five original (lowest) frequencies. The additional frequencies (4 on 866 and 867) were added because MAPS really hogged up the system, causing fire and police units to receive many busy signals during the day.
