As someone involved in the implementation and maintenance of the radio system for my company...., there is a lot of misunderstanding surrounding radio systems these days....the majority of Public Safety, Fire, railroad, utility companies, etc have gone to P25 Digital Trunking systems, largely for the interoperability. Part of the P25 specifications demands that no one radio manufacturer can make it so only their radios will work on their system, and this was done largely to take away Motorola's huge monopoly hold on the 2-way radio market. This also has the benefit of allowing smaller agencies with much smaller budgets to have access to better and larger radio systems without the capital investment of a full system themselves (generally we're talking many millions of dollars to implement a full system). Basically this means that a smaller agency can have access to our radio system's "backbone" to obtain the statewide coverage that we have without having to purchase and maintain all the "behind the scenes" equipment to support it. It also makes it very easy for their personnel to communicate with our personnel over the radio system. Kind of like a small company leasing space on a radio tower without having to own or lease the land, erect the tower, provide power to run it, or maintain it. They only supply the antenna to hang on that tower, and pay a leasing fee for it. We actually several agreements with the Forest Service, BLM, and a couple smaller public safety agencies that do this on our system.
P25 Digital Trunking in and of itself does NOT prevent the use of scanners to receive the signals, nor the ability to decode the signals into usable audio that you'll understand. Yes, the older analog scanners will not do this, but it's not that they won't receive the signals, rather they just lack the ability to decode the digital into audio you can hear. Look up P25 scanners - many of them on the market. For the most current support, you'll want one that supports P25 Phase 2. Generally all you need is the scanner, and the WACN ID number of the system you want to monitor programmed in, then you're good to go. Several websites are out there that list many of the agencies across the country, and their WACN, such as
RadioReference.com - Scanner Frequencies and Radio Frequency Reference
As far as the encryption goes, yes, there are an increasing number of agencies utilizing this, but it's rare to find _ALL_ of their radio calls being encrypted as it places a HUGE load on the radio system for no real gain. My company's radio system rivals the size, complexity and cost of what major metropolitan police agencies would have, and less than 1% of our radio calls are encrypted. What you'll often find now are general dispatch channels are not encrypted, and some car-to-car channels are not, but things like channels intended for tatical operations where high levels of security are needed, or channels for things like officer to dispatch for verifying people's identification/license status/etc where personal identifying information will be transmitted, are encrypted. There is also a very high number of operations that are done via cell phone and mobile computer these days, which no scanner on the market will decode without large amounts of modification. Yes, it is possible to monitor cell phone conversations today, but it is _very_ involved to do that set up, and very illegal. You're not doing it with the help of a YouTube video and cutting a resistor out of a radio/scanner, like we did back in the 80s and 90s with scanners to pick up on analog cell phones and cordless phones. Today, those frequencies are typically locked out of the scanners via firmware programming, and not easily bypassed.
Given the rise of cell phones and wide area internet access via smartphones and aircards in laptops, the truth today is that unlike in the 70s and 80s, there's just not that much interesting chatter going across the radio waves any more. Even just 10 years ago, I did a LOT of my work over the radio, and now..the only time my truck radio or handheld radio even gets turned on is when I'm far enough out in the field that my cell phone won't work, or we're in the middle of a major disaster that has taken the cell network down.
