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A brief, introductory telecommunications signaling tutorial April 30, 2009

Posted by HubTechInsider in Telecommunications.
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Signaling is the process of sending information between two parts of a network to control, route, and maintain a telephone call. For example, lifting the handset of a telephone from the receiver sends a signal to the central office: “I want to make a telephone call”. The central office sends a signal back to the user in the form of a dial tone, indicating that the network is ready to carry the call.
The three types of signals are as follows:

* Supervisory signals. Supervisory signals monitor the busy or idle condition of a telephone. They also are used to request service. They tell the central office when the telephone handset is lifted (off-hook requesting service) or hung up (on hook in the idle condition).

* Alerting signals. These are bell signals, tones, or strobe lights that alert end users that a call has arrived.

* Addressing signals. These are touch tones or data pulses that tell the network where to send the call. A compuer or person dialing a call sends addressing signals over the network.

Signals can be sent over the same channel as voice or data conversation or over a separate channel. Prior to 1976, all signals were sent over the same path as voice and data traffic. This is called in-band signaling. In-band signalling resulted in inefficient use of telephone lines. When a call was dialed, the network checked for an available path and tied up an entire path through the network before it sent the call through to the distant end. For example, a call from Miami to Los Angeles tied up a path throughout the network after the digits were dialed but before the call was started.

Prior to the proliferation of voice mail, between 20% and 35% of calls were incomplete due to busy signals, network congestion, and ring-no-answers. Therefore, channels that could be used for telephone calls were used to carry in-band signals such as those for incomplete calls, dial tone, and ringing. Multiplying this scenario by the millions of calls placed resulted in wasted telephone network facilities.

In addition to tying up telephone facilities, in-band signaling sets up calls more slowly than out-of-band signaling. To illustrate, the time between dialing an 800 call and hearing ring-back tones from the distant end is the call setup part of the call. Call setup includes dialing and waiting until the call is actually established.

Emergency “911” telephone numbers around the world April 30, 2009

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There isn’t a worldwide standard telephone number that people dial regardless of the country they live in to reach emergency providers. Also, many countries have a set of different emergency numbers for mobile phones, fire, police, and ambulance services. As a for instance, Hong Kong uses 999 for emergencies for landline phones and then 112 for cellular emergency calls. The very first emergency number was 999, originally used in London in 1937.
The following is a partial list of emergency numbers around the world:

Argentina 101
Australia 000
Brazil 190
China 110, 119, 120
Columbia 123
England 999
European Union 112
Iceland 0112
Israel 100
Jamaica 119
Japan 110
Mexico 060 or 080
Moscow, Russia 051
New Zealand 111
Philippines 117
Poland 997
Romania 961
South Africa 112

The true meaning of “Getting someone’s Goat” April 30, 2009

Posted by HubTechInsider in Definitions, Uncategorized.
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The expression, “To get someone’s goat”, meaning to anger or irritate, originated in 19th century racing stables in England. High-strung race horses were kept calm by having them share the stables with a goat. Evidently, the company calmed them and allowed them to rest and relax. Unprincipled hooligans would sometimes sneak into the stable at night and remove the goat. The horse got upset, would not have a good rest, and lose the race the next morning.

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