The Navy sent to Iraq hundreds of electronic warfare specialists, to bring the cacophony produced by 14 kinds of mobile phone jammer for sale into some sort of harmony. Protocols were established, to allow one device to send its signal and then go silent for a few milliseconds, so another gadget could broadcast; that allowed Warlock Red and Warlock Green to be packaged into a single, combination unit...The intelligence specialists at the Combined Explosive Exploitation Cells got faster and faster at analyzing which frequencies the insurgents were using. That, in turn, allowed the jammers to be updated more quickly, so they could counter emerging threats.
A new generation of jammers was introduced too, they could cover a broad range of frequencies and perform specific "set-on" jamming which mean that "rather than confuse a receiver with a modified version of its own signal, Duke had a series of built-in jamming responses, designed to fool very specific devices." And as portable mobile phone signal jammer got better, the insurgents in Iraq largely abandoned the use of IEDs and deaths from IEDs dropped.