It depends on the type and scale of the SHTF. IN some cases the waves may be tied up massively, or jammed out if there are adversaries or individuals trying to stop communication or coordination using wireless communcations.
Telephone lines may not be tied up but they could be down. If the emergency is of large enough scale then there could be dead air as those lines will be reserved for when they are needed.
There are active nets in most areas, people chat, and they do practice net operations are actually required then they are called into action.
Groups like ARES exist for helping communications. Many major municpalities will have their own emergency operations centers, in addition to local police force emergency operations centers, which in turn will have either regular staff, or volunteer staff. Weather reporting network, emergency weather reporting individuals ect often will all be organized but may use language that you may not fully undestand. Normally scripts are used which will not give much additional information but will give the information you need to know.
Local areas will have their own local emergency plans, from a federal, subfederal and local levels, which in turn will coordinate.
The dificult part is that people are often expected to listen to the commercial areas which may or may not be coordinated with emergency broadcast system - which was discontinued, much like emergency phone reporting network was grandfathered, and the emergency notification system was inbuilt into cellphones (which can be triggered by sending the right code to a cellphone)
all in all while you can get information of insecure networks, you will need to know how to decode ham communications that use standard coding - which can be accomplished with a sufficiently powerful computer without great dificulty. Advanced communications systems however use real time random switching technologies that most people will not be able to tap into which requires a lot more computing power - it gets more complex the more advanced the system gets. Only government can legally use advanced coding technologies - the most encrypted systems tend to be newer digital cellphones (monitored by the communications companies), and some marine systems but once again these are able to be easily broken and are not secure. It is however illegal to listen into coded messages which are not intended for you.
The idea of ham is that it is not a pubic broadcast (aside from nets, local reporting, and weather, calling and a few others) however a message goes from one person to another. Of course you can listen in to open communications they really arn't intended for you which presents potential legal liabiities if retransmitting or transfering that info. False flag in an emergency is also easily accomplished since anyone with a radio can broadcast, unless it is from your net or hams you know.. it could be anyone.
All sources of information are intelligence sources, but they arn't necesarily the truth, if you trust local authorities get your info from them, you will need trusted sources, otherwise in SHTF it could be anything... wireless communications are not secure.. cable TV is a little safer but can still be spliced or implanted, not as commonly though.. but go cable or dsl for info for information reliability.
Of course if you know people the chance of computer remodeled false flag is pretty low unless it is foreign attack or a major "terrorist" organization that is acting through a coordinated false flag.
The good thing about ham is you can build your own tech and there are massive open bands in the experiemental range of the many terraherts which can be used for new and advancing technologies such as wireless seethrough technologies --- and communications.
In a natural emergency situation any communication is better than no communication. In a manmade emergency it could be a liability if the source of the disaster is aware of the advantages of wireless communications as a tactic, such as false flag or fox hunting.
SHTF covers such a wide gamut, none the less having it as an option enhances a preppers capabilities, especially for a prepper group that is spread out accross a city, or region. having your own legal channel through a unique communications method can be good, even ham digital paging network.
http://mark-rodgers.com/HamPager/
encoding messages is not legal, the grey area is encoding hardware which may be legal, but that is not legal advice.