The methods used to pass on urgent messages or warn people of danger have evolved greatly from the days of sending runners. For instance, a story is told of a Greek long distance runner, Pheidippides, who ran two hundred and forty kilometers in two days to ask for help to repulse Persian invaders. For more modern emergency communication equipment Pennsylvania has a large number of suppliers.

Such devices have to meet a number of criteria. The first is that they must be highly reliable; failure is not an option in the middle of a crisis. Had the modern Athens Marathon commemorates the run of the soldier failed, Persians would have overrun Athens. They must also be secure; it would not do to find some parts of the apparatus stolen, or for a person with ill intent to sabotage it. For instance, it was extremely critical that hero of Ancient Greece stay out of enemy hands.

Had he been captured, the information may have been extracted from him, or he could have been killed. Either way, the message he was sent to deliver wouldn't have gotten through, and the Athenian's goose would have been cooked. Paradoxically, they must be easily accessible too, at least to authorized personnel. Finally, they must be able to get the message through quickly to the intended recipients.

Pheidippides was successful on all points, making him a valuable messenger. Unfortunately, he did not live long after delivering his message. When Spartans defeated the Persians, he ran another forty kilometers to Athens, where he died after delivering the good news of victory.

These devices can be classed into two categories. The first is those designed to deliver messages to individual points, such as mobile phones, walkie talkies, among others. The second is those meant to deliver messages to a large number of people at once, such as public address systems, digital signage and so on. Devices meant to pass messages to the public must be able to get through to as many as possible at the same time.

For instance, a message that relies purely on a light emitting diode sign may fail to reach the visually handicapped, while one that relied purely on audio may fail to reach the deaf. It is essential that the two be combined for maximum reach. In practice, messages that incorporate both visual and auditory cues are generally more effective.

Some devices, such as mobile phones and hand held, portable are more personal in nature. This does not mean that they cannot receive public messages. For instance, it is now common behavior for users to post messages on social media, with these being visible to millions of other users. Because calling and texting tends to be overwhelming the capacity of network operators during a crisis, the internet may be far more reliable.

If people can't hear, such as those who are deaf, or when they are temporarily unable to do so due to loud noises or temporary deafness, then this may not be useful. In normal practice, such systems are combined with visual signs for maximum effectiveness. For anyone who needs emergency communication equipment Pennsylvania has a wide variety, but these are some of the things to consider before investing in any of it.