DERA was founded on the use of amateur [ham] radio. This is still a key communications method today.
It is very important that the communication methods map to the way the intended audience wants to receive updates.
There are other methods for message transmission via satellite phones, cellular service, voice over internet protocol [VOIP]. There are smartphones apps that assure that messages are received by the impacted people and organizations.
Text, email, internet software applications [Facebook, Messenger, Twitter, Next Door with more available every day] are all possibilities for effective communications.
The collective DERA group has a huge storehouse of knowledge regarding communications methods.
Communications Facilitates Response