About 2 years ago, a couple employees including myself began working at a new location with no wired internet access. They were given Verizon USB dongles to plug into their laptops. Including those dongles, company-wide there were only a handful of devices on this Verizon plan.
Over time, the company got more employees at the new location. We were provided a wireless hotspot (one of the verizon jetpack devices) for everyone in the office to use. Eventually we started getting messages from the company's IT department that we were using too much data. Turns out every single verizon device at the company shared a single 60 GB data cap. Our device alone used like 15-20 GB. It only takes a couple devices used like that to blow past the data cap.
Since the company was adding new employees at the new location, as well as giving out more dongles, we managed to get them to switch to a larger data plan. I think it was 80 GB. As you can probably guess, it didn't take long to go over the cap again. Finally, some time late last year we were told by IT that the company switched to an unlimited data plan. No more caps.
Fast forward to the last 3-6 months. Like clockwork towards the end of the month the internet is slow as hell in the office. I would clock it in the 20-70 kbps range. We check the display on the hotspot and the data usage section says "Data usage: 26 GB / unlimited". I call our IT department and am told, "that's really strange. Let me call Verizon."
The next day IT calls me back. I get told "You're not going to believe this. The company data plan is unlimited. Verizon has a per-device cap at 22 GB, and then they throttle the connection. They want such an exorbitant fee to increase the device cap that it was cheaper for me to order a hotspot for everyone in the office (about 4 or 5 new devices)." Since we had a bunch of local devices set up on the jetpack's LAN, now whenever we hit the 22 GB cap and get throttled, we just swap in a new SIM from another device.
It really makes me laugh though, because when we have a few devices using roughly 15-20 GB each, Verizon had no problem letting us blow past the 60 GB data cap. None of the devices throttled the connection. The company would just receive a bill with hefty per-GB overage charges each month. When we switched to the 'unlimited' plan, IT was just as surprised as we were with the throttling. That was the whole point of the 'unlimited' plan.
This is one anecdote. But the fire department's experience reminds me way too much of the experience at my company. It's possible that both the fire department IT and my company's IT didn't do their due diligence. But my instinct tells me that verizon doesn't always make it clear that "unlimited data plan" is "unlimited data plan with a per-device cap, and subsequent throttling," especially if you are switching from a capped multi-device plan to an 'unlimited' multi-device plan.