About PBX (Private Branch Exchange)

PSTN (Public Switched Telephone Network)

Public Switched Telephone Network, more popular known as PSTN. It is a type of phone system that carries analog voice data through electronically switched network. This is your typical landline phone connection.

Drawbacks of PSTN

As a dedicated service, the line cannot be used for any other purpose while on a call. One phone number is equivalent to one phone line. suppose you have a office with two or more departments and each department needs public telephone line, so each call initiated from the company or office cost money. Calls from one department to another, or one employee to another whose cabin is nearby or just down the hall (within the office) will be charged.

Business owners needed a way to handle internal and outgoing calls in a more cost-efficient manner then PBX came into the picture.

PBX (Private Branch Exchange)

PBX stands for Private Branch Exchange. It is device that links all the phones of office together and allows connection among them free of cost. It uses an internal numbering system for internal switching. You'll only need to dial a three or four digit number (extension number) to make a call within the office or internal network. It allows a company to have a single phone number that people can use to contact a number of different internal representative.

TYPES OF PBX

There are mainly 4 types of PBX based on function, they are

1. Analog PBX

2. Digital PBX

3. IP PBX

4. Hybrid PBX

1. ANALOG PBX

Analog PBX uses for analog phones. They use POTS (Plain Old Telephone Service) line. They are reliable and provide good voice quality but have limited features like hold, mute, redial, and speed dial. Some companies use analog phones because good voice quality, and low price.

2. DIGITAL PBX

Digital PBX is designed for more modern phones known as digital phones.  Digital phones have some advanced features like  voicemail delivery to email, fax delivery to email, voicemail transcription to SMS etc.

Cabling structure for analog and digital PBX

Note: In a network that has Analog or digital PBX needs separate cabling structure, one for voice and other for data.

3. IP PBX

IP PBX is a telephone switching device that switches calls between VoIP (Voice over IP) on local line or between VoIP and traditional telephone users.

Advantages of IP PBX over Analog and Digital PBX

1. Single Network: In IP PBX, there is no need of double cabling structure one for voice and other for data. With IP PBX, the computer network can be used to carry voice calls along with data and IP phones connect directly to the network switch ports using Cat-5 or Cat-6 cable. This is one of the biggest advantage of IP PBX. 

2. Inter-branch Calls:

Multi-site calling is free, If IP PBX has been deployed in multiple branches of the same company. Normally MPLS or Internet leased lines used between different sites for connectivity.

3. Video Calls

It is possible to make video calls with IP PBX. Video call supported IP PBX and Video phones are required for this purpose.

4. Long Distance Calls: 

It is possible to make International calls through the internet for lower cost.

3. HYBRID PBX

As the name suggest, it is hybrid because it allows both IP and TDM extensions. The advantage of the hybrid PBX is that it cuts down the costs of a total migration when a company wants to upgrade old TDM to VoIP.

TYPES OF PBX BASED ON DEPLOYMENT

There are mainly two types of PBX based on deployment, they are-

1. On Premises PBX

2. Hosted PBX/ Cloud PBX/ Virtual PBX

1. On-Premise PBX

An On Premises PBX is a PBX that resides on the premises of the company that uses the PBX. It is also known as on site PBX. 

Disadvantages: 

1. Higher Setup costs because you need to purchase PBX

2. There are higher costs for installation, operation and maintenance.

3. Training is also required to learn how to run the phone system, how to add extensions and so on.

Advantages: 

1. New open source features can be added without any licence fees.

2. No risk of fee increasing

3. You have control over every detail.

2. Hosted PBX

Hosted PBX is a PBX where service provider is responsible for housing the PBX as well as handling the technology required to provide the services to the phone system. It is also known as Virtual PBX or Cloud PBX.

Advantages: 

1. lower setup costs and no maintenance costs.

2. All the major software updates and maintenance processes are handled by the service provider.

3. Quick setup and maintenance.

Disadvantages: 

1. Your service provider has the actual control over your system.

2. Service providers can change their fee at any time.