This Device complies with part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) This device must accept any interference received, including interference that may cause undesired operation.
An electromagnetic pulse, and the resulting resistance heating of energized components - can be interpreted as a rather massive form of interference. And since things with antennas are designed to collect and amplify incoming EM signals - well most communications equipment was devastated by the Electromagnetic Pulse of the event - both alien generated an human nuclear weapons. Orbital communication satellites were also damaged by either pulses or deliberately shot down to deny humans military cohesion (it cannot be said often enough - Citizens are a lot smarter than the average movie invader).
However, the blackout was not total. Technologies like cellular communication and distributed computing meant no one element would take down the entire com grid. Furthermore, there were plenty of radios built to either military shielded standards, or by luck were stored in a place with enough shielding to be unaffected. Micro-facs have succeeded in producing new equipment as well, though it will take some time until phones are as ubiquitous as they once were.
Long distance communication is unlikely. With no maintenance on much of the cable network - tremors, flooding, animals, and other such natural phenomenon have rendered most hard-lines. As stated previously, the satellites needed for the other form of long range transmission are gone. AM radio at night, when signals can be bounced off the ionosphere and travel several times father than their day-time range - though this still limits intentional links. Of course, even if inter-continental communication was possible, the ability to act over those distance is lacking.
Couriers have become a major network for information. Convoys will of course carry mail, and some city states maintain professional delivery services for important missives. A few small groups have even tried to start a national mail service, though they are still competing with each other than a unified whole.
This leaves a place for players as those trying to pass along messages, interfere with them, or even as civil engineers placing new cell towers and helping bring back the network. Exciting as a run through a reanimate infested factory complex might be, there is a need for the long term. Becoming the lords of a telecommunications fiefdom could end up far more enriching than raids on old factory complexes.