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How Does a VoIP PBX Work?

VoIP phone service background
VOIP | VoIP Services

For decades, companies have used PBX systems to handle communications. PBX hardware can be used to route and distribute incoming calls from external lines to a number of internal lines.

It ensures that a company need not have a separate, dedicated line for every employee by making it more efficient to share lines.

It also allows workers in the office to talk to each other via extension numbers – usually two or three digits – instead of having to dial phone numbers each time.

Gradually over the last decade, organizations have replaced analogue PBX with VoIP PBX systems (also known as hosted VoIP PBX systems).

You might also like:
What a Cloud PBX is
What a Hosted PBX System is
Advantages of Hosted PBX Systems
How to Create a VoIP PBX
Cloud PBX Advantages

What Makes VoIP PBX Different?

VoIP PBX – also called IP PBX – can switch between VoIP users so that external lines can be shared among employees.

These boxes can also handle traditional users or switch between VoIP and traditional users. Fundamentally, a VoIP PBX handles VoIP calls in the same way that a conventional PBX box handles analogue calls.

For the most part, the end user experience does not change. Employees can still answer calls normally and make calls to internal or external numbers by dialling.

However, the underlying technology and architecture is what sets VoIP PBX hardware apart from conventional enterprise boxes.

How Does VoIP PBX Work?

A VoIP phone system usually consists of the following components:

  1. SIP phones
  2. VoIP PBX server
  3. VoIP Gateway – optional

The SIP phones can be soft clients or dedicated IP desk phones. The endpoints may even be computers equipped with microphones or mobile devices with VoIP clients. The VoIP PBX system acts as a server and all the phones in the enterprise are registered on it.

The server has the database of all phone numbers in the organization along with the SIP addresses of the client phones. SIP is the most commonly used protocol for VoIP implementations and it is compatible/interoperable with most major VoIP services, hardware and providers.

Incoming calls are directed to the appropriate user by looking up the SIP address. Outgoing internal calls are directed to the particular employee according to the respective settings (go to voicemail, directly to cell phone etc.) and external calls are usually routed to the VoIP gateway.

The gateway can connect to both PSTN and ISDN lines, so that it can span multiple networks. On the other hand, external calls can also be directed to the destination through a VoIP service provider.

VoIP Gateways

The VoIP gateway may be incorporated into the system itself but many organizations prefer to use gateways provided by the VoIP service provider. VoIP gateways are used to connect the system with the PSTN network.

PSTN phone lines are usually connected to the VoIP system through FSX and FXO ports, depending on the direction of travel. VoIP gateways may be available as dedicated devices or installed as PCI cards.

Virtual VoIP PBX

Most VoIP PBX features are controlled and configured by software. This means that the system need not always have dedicated hardware.

Sometimes the VoIP PBX is simply a combination of hardware and software installed on an ordinary PC, performing the same functions as a regular VoIP PBX. It is referred to as a virtual VoIP PBX.

Hosted VoIP PBX

Although VoIP PBX systems offer many advantages, the organization still has to purchase, maintain and upgrade the system periodically. This process requires resources – capital, personnel and time.

This paves the way for hosted PBX, wherein the vendor will purchase and maintain all equipment required to provide VoIP services and an organization simply has to sign up for a plan to start making calls.

All the features traditionally associated with the physical PBX box are provided over the Internet using cloud technology. It frees up the organization’s resources and they can be directed to more productive uses.

Advantages of VoIP PBX

One obvious benefit is the tremendous cost savings, especially for internal and international calls. Since these calls travel over the Internet, they are essentially free for employees who are registered on the same corporate network.

Similarly, international calls will cost a fraction of what is charged by carrier operators since they don’t travel over the PSTN network.

VoIP PBX systems offer all the business features that companies have come to depend on. Caller ID, voicemail, conference calling etc. are all supported and users will have no difficulties in switching over to the new system.

Quite often, existing features improve upon and integrate better with the other digital systems being used by organizations. A good example is voicemail that is considerably enhanced by using VoIP PBX.

Voicemails can be forwarded to the employee’s email address, this allows users to categorize and manage their voicemail just like the handle other email messages.

Additionally, VoIP PBX systems allow employees to have granular control over specific settings. For instance, an executive can configure the system to automatically forward incoming calls to voicemail during a particular time of the day while still allowing calls from customers.

Alternatively calls from a particular number can be forwarded to a mobile device will others are directed to a secretary’s number. This allows flexibility for employees who are traveling, working from home, operating from a client site etc.

Should You Switch to VoIP PBX?

Switching over to VoIP PBX makes sense for organizations that prefer to have control over the enterprise network. However, it does mean that the company has to have the personnel who have the requisite knowledge and experience in installing and maintaining VoIP systems.

Sometimes, the entire network will have to be overhauled in order to provide additional bandwidth for VoIP calls, new IP phones for employees, optimizing the wireless/wired network etc. which can turn into an expensive and time-consuming project.

Hence many organizations – especially small and medium businesses – prefer to use hosted VoIP services so that they can enjoy all the benefits, without shouldering the maintenance and set up.

Even if the final VoIP deployment turns out to be more expensive than planned, it can still provide tremendous benefits in terms of increased efficiency, decreased costs and advanced features.

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