One aspect of governmental security is domestic security, and within that one critical ability is the ability for governments to effectively communicate with their citizens. The types and extents of communication are both broad and diverse, from communication of emergencies (alarm systems, siren systems, 911), to propagation of “good to know” information such as governmental benefits available to citizens, to important national news such as elections and foreign negotations.
In particular, one system that is highly benefitial to security is the 9-1-1 system.  In short, it is a catch-all phone service for residents to report incidents that require immediate emergency response, for example a fire or medical emergency. Telephone technology has greatly assisted this effort, both providing the underlying network as well as various enhancements, such as the ability to locate callers and relay this information to the dispatcher. In recent years, the system has even been extended to geolocation of mobile callers, or allowing citizens to send text messages to the dispatchers. This fosters a relationship of trust where citizens know that the service will be available for them when they need it. In December 2017, over 98% of the population of the US has access to the service. 
With respect to citizen understanding of the technology, the phone system is fairly well understood. However, new developments in mobile technology may be unintuitive. For example, geolocation of mobile 911 callers is still fairly limited compared to geolocation of landlines, and citizens may be unaware of this fact, even though over 70% of calls are now made with mobile devices.
Another system is simply government pages on the web, which are effective ways of disseminating useful information to all citizens. usa.gov  is a prime example of this. On the website, one can find a trove of information. There are links to veteran’s benefits, tax help, social security and medicare/medicaid, even pages containing information about the organization of the government and election data. Ready to access to such information would have been much harder in the days before the internet, probably requiring several phone calls or visits to government offices. Now, citizens can be more informed than ever before.
However, citizens should be careful to understand the nature of the internet. It is trivial to set up false sites that look like the real usa.gov website, but contain propaganda or false information in an attempt to mislead citizens. Citizens should know how to determine if the website is fake or not, for example by recognize the .gov top-level domain, or ensuring the https lock sign is present.