Hmm, "Terrorist Jamming" not exactly a new idea, but has not happened as far as we know...
Have you ever wondered why?
Simple answer if you have the brains and skill to perform this type of trick you can be a lot more creative. And your creativity will get you a better bang for your buck.
That is 650USD will get you more explosives, weapons, etc all of which will provide rather visceral feedback via news reports very rapidly providing a high impact for the expenditure.
Jamming the emergancy responder comms won't provide any more visceral feedback, and it might be weeks or months before it actually becomes news by which time it won't effect the initial shock the terrorist is looking for.
So from a terrorist point of view it has a rather low ROI. Which is made worse by the fact that you will need skilled personnel to do the jamming over any kind of wide area. And other things such as area jammed is more related to the hight of the jammer not it's power adds needless complexity and risk to the whole operation.
So what about high value crime not terrorism? here there might well be an advantage to jamming the first responder networks. But again only for a skilled and well disciplined team.
So what about techno-vandals such as groups of hackers doing a DoS style of attack. They certainly have the skills but in general such people have little or no funds so the 650USD cost of entry would in all likelyhood act as a deterant. Plus
as noted above if jamming becomes a problem the source can be fairly easily traced, it's a question of response time which would after the first one or two attacks become very rapid. And then there is the tracable physical evidence, and the prosecuters and courts are not going to see this as anything other than a direct attack on society equivalent to a serial killer etc so they are going to be looking at handing out multiple life sentances with no hope of remission to enssure the point got across to others.
But there is a catch, if you have the brains to do it and a little skill with a soldering iron and a bit of experiance building amateur radio equipment you could probably make a jammer for a lot lot less than 650USD. Possibly as little as 10-20USD with parts from "other projects" including broken phone parts.
Now there might even be a market for such devices, you can already buy cheap jammers for other cell/mobile technologies which have (supposadly) been used by restaurants, theaters and other entertainment venues where mobile phone use is considered inappropriate by the venue operators for various reasons.
If such devices do become available fairly cheaply and effectivly anonymously and local LEO's do switch to using 4G then yes you might find petty criminals using them to improve their get away chances.
Of interest in this respect is the UK's Met Police in London after 7/7 there was a whole load of political time wasted over the fact that first responders could not talk to each other especialy underground etc.
Well part of the fallout from this is TETRA which is a trunked PMR system. Unfortunatly it's not workiing out at all well for various reasons and you will see very many Met Police officers with two or even three mobile phones they use in prefrence to the TETRA system for a whole host of reasons.
Now thiss "add hoc" network via mobile phones has a significant problem which it appears nobody in authority has picked up on yet. Which is what happens when we have another 7/7 and the mobile networks stop operating (as happened on 7/7). Many officers have got so used to not using TETRA that come such an event as 7/7 then they won't be able to use TETRA effectivly or at all.
Oh and as it happens TETRA and other trunked PMR systems are possibly even easier to jam for similar reasons to those given in the 4G article...
The real issue is actually "penny pinching" in the name of "efficiency" by those who hold the purse strings of LEO's and other emergancy services. They are not realy interested in robust communications for emergancy services if they can do things on the cheap. In the UK we have seen this mentality with the Ministry of Defence not supplying UK troops in Afghanistan and Iraq with appropriate and necessary equipment with the result that people on the ground have died needlessly on repeated occasions. But that's OK as long as the procurement people at the MOD get their bonuses and cushy jobs as lobbyists and directors of defence contractors.
I would fully expect exactly the same issues to occurre with the idea of using mobile phones for first responder critical communications. After all if it goes wrong what will happen? the politicos will hold an enquiry to exonerate themselves and others and make statments like "this should never happen again" and then through lots of money at some other boondongle solution (just as we do with body scanners).
As was once observed about NASA astronauts, they were very brave people put into space by the lowest bidders...