Emergency notification | Technologies and Methods

Fully Interactive Two way methods:

Telephones

Modern touchtone telephones use DTMF tones to talk to the phone switch. By exploiting DTMF, you can get proof that a recipient has received a message by recording their respones.

Advantages:

• Telephones allow for a live conversation

• Highly secure since message itself can be passworded

• Computer readable responses can be entered from a telephone keypad

• Practically everyone has at least one or more telephones

• Telephone call lists are part of nearly every existing emergency notification procedure.

Disadvantages:

•  It is expensive to maintain multiple phone lines to place calls

• Emergencies can severely limit available resources on the public phone switch

There are two ways telephone connections can be made:

Analog are the most common. They can either be outside lines provided by the phone company, or operate as an extension from an internal switchboard.

Digital interfaces come in several different types, ISDN-PRI, ISDN-BRI and VOIP. With Notificaiton systems, ISDN PRI is most common because of how efficiently and reliably it handles calls.

Private Radio

Private radio networks is mentioned here since it's a fully interactive two way method. But it's not used very frequently in emergency notification.

Advantages:

• Private radios can be portable

• Live conversations

• Ability to broadcast messages or tones to groups

Disadvantages:

• Difficult to interoperate between different radio systems and frequencies

• No standardized solution for collecting responses to messages such as DTMF

• Broadcast is one way communication

Store and Forward Messaging or delayed Two way methods:

The type of equipments listed below are all of the store and forward type. Some Emergency Notification solutions are able to accept a message back thus making them to "delayed Two way equipment". Below is a list of advantages and disadvantages for all these methods:

Advantages:

• Store And Forward

• Often Highly scaleable

Disadvantages:

• Depends on separate communication by recipient to respond

• Message traffic subject to delays outside of activators control

• May require specialized devices

• Can't password message itself

Answering Machines, Voicemail

Answering machines allow telephones to act as store and forward message systems. The activator of a notification does not know when a recipient listens to the message, only that the call was made and a machine was reached. Some notification systems attempt to detect answering machines.  Other systems do not attempt to detect a machine, but simply initiate the sequence of messages based on sound when the phone is answered. Answering machine detection fails at least 25% of the time, and inserts a delay at the beginning of the call. Sound triggered calls will report that a recipient has not responded, and continue to the next device or individual.
For Emergency Notification, machine answered calls are considered failed and must be retried at an alternate number.
 

SMS/Text Messaging/Pagers

One way and Two way text messaging devices ordinarily should be treated as one way methods in the context of Emergency Notification since it is difficult to verify receipt of an outgoing message, and it is difficult to know when a reply will be received. Normally, it is safest to expect the recipient to call back into a call center, or an emergency notification system to confirm receipt.
 

Addressing SMS/Text Messaging devices

Cell phones, pagers and other text messaging devices can have different addresses for devices accessed within a network and from outside of a network. Similarly, traditional TAP compatible Pagers must be addressed by an Emergency Notification system with different phone numbers for each paging company used within an organization
 

Email

Email can be sent quickly, in large quantities and is very standardized. Many different types of equipment can receive messages: cell phones, pagers, PDA's, as well as computers. Messages travel on public networks, and are subject to switching delays which can be unpredictable.

Faxing

If you need to send pictures or other documents use a fax. While a sender may know that a fax machine received a message, often a separate telephone call is necessary to alert someone to the incoming fax, or to confirm that the message has been read.

Announcement Systems:

Speaker systems and local AM Radio

Many notification systems can activate separate Emergency announcement systems, if there is a telephone interface where a message can be played after a DTMF based authentication.

 

Fire alarms, Sirens or Control equipment

If a notification system can control operate a programmable logic controller, alarms or equipment can be automatically turned on (or off) depending on requirements. With PLC's connected to a industrial machine, or valves, typically a separate call is necessary to notify staff that the device was tripped.