Systems,
Army bomb squad teams frequently sweep buildings for devices and carrying out jamming. The types of UK applications are Political Conferences etc.
They use antenna on vehicles to sweep a building to locate and transmitters that have been hidden and also to send out jamming signals across frequencies known by intelligence to be used by threat groups. As I understand it the technology isnt all that complicated. However that works on a static building, not as effective over a large area such as a higway that runs for many miles.
When mobile phones are used the situation becomes more complicated, in the age when everyone has them it would be fine if you knew what phone to actually look out for. Cell site analysis works when you have some control over the network operators, it is possible to get a fix with some degree of accuracy on a particular phone and it is possible to surveil that phone as it "pings" to the nearest phone mast.
However in Iraq that would be difficult unless the coalition had some form of control over the telecom supplier. It could be a potential tactic to trace the bomber after the event. In theory when a roodside bomb went off, the mobile network nearby could be interrogated to find out what phones were active at that time in the vicinity, once you narrow down a particular handset of course, you would then have to hope that the chap wasnt "pay as you go" and not registered to that phone, and that you could actually get a subscriber check done in Basra!!