Advanced Telephony Switching System for Business CommunicationMan using phone

IP PBX plays a vital role in today’s corporate telephony infrastructure. This advanced telephony system attempts to replace proprietary PBX to reap significant benefits for most organizations. It’s emerging as a cost-effective business solution for enterprises to replace the POTS (Plain Old Telephone Systems) with full voice delivery capability. The term IP PBX1 indicates the Internet protocol (or IP) based private branch exchange that is shaping to be the de-facto telephone switching system within an enterprise.

IP PBX is a complete telephony system and provides telephone calls over IP data networks. The major benefit of such an IP based system is that it sends conversations as data packets over the Internet. This technology not only has a lot of advanced communication features but also provides a significant dose of worry-free scalability and robustness that all enterprises always look for. Also, the IP PBX is able to connect to traditional PSTN lines via an optional gateway – so upgrading day-to-day business communication to this most advanced voice and data network is a breeze! The enterprises don’t need to disrupt their current external communication infrastructure and operations. With IP PBX deployed, an enterprise can even keep its regular telephone numbers. This way, the IP PBX switches local calls over the data network inside the enterprise and allows all users to share a certain number of external phone lines.

As far as evolution is concerned, the growth for IP PBX above will first take place via IP enabled PBX (Converged TDM and IP PBX) and then to a “Pure All IP” PBX.

IP PBX evolution diagram

Benefits of IP PBX

Benefits of IP PBX table


Reduced long distance expenses via toll bypass

A major advantage of IP PBX is that it can avoid tolls charged by traditional telephone services by utilizing fixed charge IP network services such as broadband. Since access to the Internet is available at local phone connection rates, an international or other long-distance call will be much less expensive than a traditional call arrangement.

Reduced costs for wiring and cable

Since the voice calls travel over data networks, enterprises don’t need any more voice wire installation, testing and maintenance; existing data wires should suffice. Enterprises also don’t require any phone patch panels, and Technology worktraditional PBX. In fact, there are no T1 voice channels to connect to remote branches when properly networked. An intranet data network enables the enterprise’s IP PBX to reach all these branches while bypassing phone companies. This is a substantial savings for an enterprise. Enterprises can also benefit from substantial savings from the fact there is no separate PBX needed for each remote (reasonable size) branch or plant. One IP PBX is sufficient to serve the headquarters as well as those remote branches or plants.

There is less maintenance cost, as there is no telecommunications department to look after, since the data-networking group can take care of the IP PBX. Its maintenance is much easier than with the traditional phone set up.

Lower equipment costs because of standardization

IP PBX is continuing its solid march towards Industry standards, e.g. SIP for signaling. Enterprises benefit greatly from these standardization efforts. For example, standardization always leads to lower cost because of increased market penetration (size). In fact, enterprises can reap the benefits of standardization in terms of better price/performance, lower total cost of ownership (TCO), availability, deployment advantages, new technology refinements and newer products and services.

Cost savings as calls are IP based – both control/signaling, and bearer being on a shared data network

Enterprises not only save cost because of toll charges alone. One direct cost savings is in the form of managing only one network for both voice and data – this avoids access charges and settlement fees, which are particularly expensive for certain companies. One example will prove this point. For example, if an enterprise decides to upgrade the Internet connection to data T1 ($300 per month) to accommodate the additional IP voice calls, the enterprise can make 50 simultaneous voice calls. However, a Telco can provide only 8 phone numbers with that cost.

Other cost savings

  • Enterprises can now save costs for traveling users. It is now less since IP phone or PC softphone can be hooked up to the internet in a hotel or hot spot for a low fee or for free.
  • There is no need to print additional business cards and stationery when employees move to a new area code since an IP PBX can forward calls to their existing phone numbers.

PBX diagram


High call quality (as well as availability and reliability)

Enterprises demand a very high quality for voice calls. In addition, the enterprises also demand carrier-grade reliability and availability (~99.999% up time). In the enterprises, the quality and reliability of IP PBX is very high. Voice quality approaches toll quality because corporate networks do not have QoS (Quality of Service) issues that currently plague the Internet.

Availability of dial tone and a suite of PBX services

IP PBX vendors offer enterprises a wide range of telephony features, from basic dial tone to a rich set of high-end PBX (e.g. such as transfer to and dial an extension) features and applications. This allows the users to get the same feel as normal telephone users from a carrier-grade telephony service provider and previous digital PBXs.

Also, IP PBX performs all the functions of a traditional PBX such as handling conference calling, transferring of calls, connecting the employees to the network using their extension numbers and many more.

Web-based configuration and management

Enterprise users can easily install, configure and manage a network with today’s IP PBXs. These IP PBXs come with a web-based configuration utility. It is very easy to integrate in an existing office In addition, these PBXs also come with web-based administration and management that is easy to use for monitoring the network. It eliminates the need for training, improves configuration and organization of applications

No need for separate phone wiring

As IP phones can use the cabling/wiring from the already deployed local area network, enterprises don’t need any more voice wire installation, patch panels or traditional PBXs. Existing data wires should suffice.

Software-based IP PBX is far less expensive than a hardware-based PBX

An IP PBX can be either hardware-based or software-based. In the enterprise, the IP PBX hardware resides behind the traditional PBX, which effectively means that calls continue to be routed via the existing PBX. Additional configuration is required to IP-enable the existing PBX. Software-based IP PBX is a cheaper option as it eliminates the need to use expensive telephony cards as software applications can connect to IP PBX easily over the network. It is also easy to configure and install, and, at the same time, requires low-maintenance.

Receive and make calls via the standard PSTN

The IP PBX is able to connect to traditional PSTN lines via an optional gateway. With IP PBX deployed, an enterprise can even keep its regular telephone numbers. This way, the IP PBX switches local calls over the data network inside the enterprise and allows all users to share a certain number of external phone lines.

Availability on different OS platforms, with significant penetration for Windows based IP PBX

IP PBXs are available in different OS platforms, such as Linux or Windows. Considering the huge deployment of the Windows platforms, especially in the small and mid-sized enterprise categories, Windows based IP PBX are becoming extremely popular due to its user-friendliness, security, quick training, lower installation costs and quick deployment. Windows IP PBX also integrates more easily with other applications.

Moving offices within an enterprise

If a user moves offices within an enterprise, there are no changes in the wiring or IP PBX configuration. Moving, adding or changing of a phone set just involves a change in the IP PBX database.

Easy development of a collaborative communications network for geographically dispersed employees

The IP PBX provides an easy and convenient way to connect an enterprise’s satellite offices together seamlessly without expensive capital and without changing out existing equipment.

Open SIP Standard – The Signaling Framework for Standard Based IP PBX

The enterprise’s choice is clear when selecting an IP PBX that’s extremely critical for their business. As always, the enterprise and its users’ community always feel easy with standard based business tools or systems; IP PBX is no exception. For the last few years, the IP PBX vendors are increasingly adopting Open SIP standard – SIP being the protocol of choice for signaling – to build standard based PBXs.

The Session Initiation Protocol (SIP) is a signaling protocol used for establishing sessions in an IP network. In addition, the vendors can also provide a host of innovative services such as voice-enriched e-commerce, web page click-to-dial, Instant messaging with buddy lists, and IP Centrex services. The most important advantage of using SIP for IP PBX is that it is an RFC standard (RFC 3261) from the Internet Engineering Task Force (IETF), the body responsible for administering and developing the mechanisms that comprise the Internet. Any IP PBX that is based on the SIP standard allows the enterprise to use SIP phones (software and hardware) and SIP based gateways, thereby making it easier to manage itself. SIP also facilitates interoperability, application development and implementation. The advantages, in a nutshell, are:

  • Liberating the enterprises from the high purchase and management costs associated with proprietary PBXs
  • Allowing the enterprises to choose from many SIP based hardware phones instead of getting locked in with one vendor
  • Eliminating the need for expensive, and specialized installation and management know how.
  • Saving on call costs using any SIP IP service

Additional benefits for SIP Phones

Mobile Extension: SIP Phones allow users to carry extension with them. The extensions are not limited to the office as the SIP device has mobile access. It could be via a notebook, Wi-Fi phone, or IP phone, provided there is a connection to the Internet.

Reduction in roaming cost: Using SIP PBX, the enterprise can save on the huge expense of roaming costs on business trips. The extension call is totally free no matter where the extension is.

Comprehensive PBX feature: The SIP PBX has comprehensive PBX functions, including: transfer, pick-up by others, forward, barring, seizes remote trunk (local or remote site), and trunk group.