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PBX (Private Branch Exchange)

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A PBX is a privately owned phone system that is commonly called a switch because they work electronically just like the old “switch boards” where a person physically made your connection.

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Meridian PBX with multiple expansion modules

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This privately owned system is a hosted PBX and does not rely on switching equipment that is provided or operated by a common telecommunications carrier, instead the system is self contained and devoted specifically to one subscriber

A PBX essentially takes the place of the Central Office within the company by acting as the exchange point, routing calls.

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The primary purpose of a PBX sometimes referred to as PABX (Private Automatic Branch Exchange) is to connect a number of outside lines to many internal telephones, including the interconnection of internal phones

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In general, hosted PBX phone systems of all types require an internal switching network that is programmed for routing to extensions, as well as voice mail boxes for each user.

A central processing unit handles the inbound and outbound traffic for each authorized node on the PBX phone system

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A PBX system consist of: A microcontroller for arbitrary data processing, control and logicLogic cards, switching and control cards, power cards and related devices that facilitate PBX operationTelephones (stations) and attendant consoleUPS (Uninterruptible Power Supply)It requires outside trunk lines, internal wiring, jacks, termination blocks and amphenol connections

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With a PBX in place, each phone only needs an extension, not a phone number, and the PBX handles all calls made from desk-to-desk within the company

One general distinction of a PBX is that an access code (usually the digit 9) must be dialed or pressed on an internal telephone to obtain an outside line

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PBX systems can be bare bones or feature-rich, depending on what the customer is willing to pay.

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A PBX reduces cost because the company only pays for the number of lines needed to be connected at any given time to the outside.

If a company has 100 telephones, it's unlikely everyone will be making an outside call at once. Perhaps only 10% will require an outside line at any given time. Therefore the company would lease 10 lines from the phone company rather than 100.

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Small PBXs that can be used in a home or small business can be purchased for about $100 - $1,000 USD, depending on features.

Larger PBXs handling up to 75 lines start at about $1,000 and can go as high as $10,000. Robust systems handling up to 20,000 lines are also available. These systems start at about $100,000 and higher

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A significant feature of a PBX is control over the numbers that can and cannot be dialed from within the system.

This can prevent calls abroad, to 900 numbers, or to other costly numbers that would be available without the system in place.

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A PBX provides one single number that external callers can use to access all persons in a company.

The PBX connects internally via 3 or 4 digit numbers called extensions

It distributes calls to employees in an even way; using the Automatic Call Distribution (ACD) feature.

It can automate call answering, but offering a menu of options from which a user can select to be directed to a specific extension or department.

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The PBX provides system call management features like:

HoldMusic on holdCustomized hold messagesCustomized business greetingsVoice message recordingCall transferConference callingCaller IDDID (Direct Inward Dialing)

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The customer must decide how calls are routed.If no-one answers…where do calls go? To someone else, to a pager, to voicemail?

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These are called Hunt Groups which are circuits used for routing calls

Hunt groups are handled by the Automated Attendant

The attendant uses DTMF codes ( Dual Tone Multi Frequency). Each button on the phone is assigned a certain sound at a certain frequency which the attendant can recognize

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The auto attendant is the voice menu that directs you to specific extension based on who your trying to reach

As an example:Pick 1 for English or 2 for SpanishFor sales pick 3For service pick 4To speak to a customer service rep pick 5To return to the main menu pick 9

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