Well...
IPN has two parts - the 72MHz subsystem is a one-way hop-by-hop relay from the paging terminal in LaPorte. The second subsystem are the UHF transmitters. Site controllers receive the 72MHz messages, store them, and using timing signals (most likely GPS) so all UHF transmitters state-wide "launch" the page at the same time.
They do offer AES-encrypted pagers. Up recently, mine worked quite well. The reason I finally put it in the desk drawer is ...
They have been trimming back their coverage area. While Fort Wayne still has coverage, I no longer have coverage in DeKalb/Steuben/Lagrange.
And least you say paging is dead - I have a client who is proposing a large Fiber-To-The-Home network. They intend to build out a paging network connected to their network monitoring system (NMS). The reason being they have letters of intent with the the big three (VZW, ATT, TMO) to provide the cellular backhaul for all cell sites in their area. When their network goes down, no way to alert the troops. For the same reason, they're putting in a P25 system - no network means no cell phones and makes restoring the network more difficult.
Last thought - a few years ago when I worked for the feds we all had pagers. We couldn't take any other kind of electronic device into our working area and we couldn't tie up the taxpayer's phones with personal calls. Spouse pages you, you leave the working area and go the cell phone charging lockers in the lobby and make your call. One day someone did the math and realized the government would save money by allowing personal calls because you'd shave four minutes off securing your workstation, leaving the area, retrieving your phone, plus four minutes getting back through security, dialing the combination in to unlock your desk drawer, logging back into your four different workstations, blah, blah, blah.
