Schools, and businesses, as well as cities and towns are adopting several approaches to alerting people in emergencies. One challenge is designing systems to reach the most people, whether they use mobile phones, office phones, or email or are located in common areas such as halls, conference rooms or cafeterias. Paging is one approach.

Paging to each telephone’s speaker
Some systems enable designated staff to simultaneously send a voice message to all or most phones equipped with speakers. Although it’s costly, Cisco offers a separate processor that enables simultaneously paging to every phone’s speaker.

Limitations in paging through phones
However, sending a concurrent voice message to each phone is not always feasible:

1. Some systems have a limit to the number of phones that can be paged at the same time.
2. All telephones may not have a speaker
3. Pages may not reach phones forwarded to voicemail or people already on their phone.
4. These alerts don’t usually reach hallways, common areas such as gyms or outdoor spaces.

Components of Overhead Paging
Overhead paging systems consist of speakers mounted on walls or ceilings that are connected by copper cabling to amplifiers. For the most part, paging systems don’t operate on fiber optic cabling. Amplifiers strengthen voice signals so that they are audible through speakers. Amplifiers are connected to a stand-alone microphone or to a telephone system. Connecting paging systems to the PBX, gives organizations the flexibility to designate which individuals are allowed to broadcast paging messages.

Zones
Because interruptions by irrelevant pages are unproductive and disruptive, many organizations design their paging systems so that some pages reach only designated areas. For example, schools that have special events in their gymnasium may want a zone specifically designed to reach the gym.

The importance of policies
Those of us who worked or went to school in locations where paging was used to routinely reach all classrooms, factory areas or hallways know how annoying it is to hear numerous irrelevant messages over loudspeakers. With today’s technology, it’s possible to allow only a few key individuals to send an overhead-paging message. These few individuals should be at a high enough level in the organization to be aware of conditions and/or be easily reached by key individuals such as console operators or department administrators.

What can go wrong?
Designing a paging system for organizations with multi-story buildings, a campus environment or outdoor areas is complex. For example, there may be fiber but not copper cabling connections to all buildings, in which case new cabling runs are required. In addition, longer runs between amplifiers and speakers may require higher grade data quality twisted pair cabling needed for distances of over 1,000 feet.

Finally, not all distributors have the expertise and experience working with complex paging systems to determine the correct number of amplifiers, how to design the paging system for multiple zones, and how to connect the paging system to the telephone system, and then how to program the telephone system correctly. In an ideal world, the paging installers have staff knowledgeable about your telephone system. This goes a long way to avoiding finger pointing.

Use of bandwidth has increased radically in the last five years. Greater reliance on the Internet, faster processors, and more online transactions, have fundamentally changed commercial organizations’ use of high-speed services. T-1 circuits, at 1.54 Mbps (million bits per second), and 24 voice channels are no longer adequate for many small and medium sized organizations.

Video and remote access
Increases in video, which consumes enormous amounts of bandwidth, legal requirements to backup electronic documents, and remote access from home, hotspots, branch offices, and hotels have driven much of the up tick in data circuits. In addition, newer, robust internal networks can now support video conferencing at lower costs than sending them over the public switched telephone network. They also adequately support video from the Internet.

How much is enough?
Finding the correct balance between adequate capacity and costly excess bandwidth is important. Many organizations focus on saving money on equipment, but neglect to manage their network expenses. The first step in managing the network is determining the busy hour load on existing links. For example, if only 25% of a link is used, there may be too much bandwidth, while 85% in the busy hour may indicate a need in the near future for more capacity. Most carriers make these types of reports available on line.

Protecting mission critical connections
For many organizations, data connections are more important than voice lines. Reliance on the Internet, email and links between sites makes dependable data connectivity critical. Furthermore, failures in high-capacity links can bring organizations to their knees.

Protection from failures
Data communications connections fail for a number of reasons:

1. Malfunctions of electronics connected to the outside fiber cabling
2. Copper or fiber line cuts
3. Central office failures
4.  Natural disasters such as hurricanes, fires, floods, and lightening strikes
5. Breakdowns in internal routers and switches

Failure protection options

1. DSL because it is based on copper, not fiber for a portion of the outside cabling protects customers from many failures in fiber’s electronics.
2. Back-up wireless Internet access such as that provided by TowerStream and Pipeline Wireless because they are operational if copper and fiber lines are cut anywhere near customers’ sites and when central offices fail.
3. In addition, wireless services can be restored faster than wireline services after natural disasters because it is less labor intensive to repair a tower than to lay new cabling.
4. Customers often make arrangements for back-up data centers for more protection during natural disasters such as floods.
5. Second routers, and dual Internet connections in the event of a router failure.
6. Duplicate power supplies, to protect against the main cause of switch failures.

The most important ingredient in planning for protection from failures, and proper network configuration is knowing traffic levels, points of vulnerability, and determining the business case for paying for back-up services.