Difference Between PBX and Centrex (With Table)

Telephonic communication within a company, institution, or any other office is very different from the local telephonic communication between houses in a city. The special layout of telephone wires a completely different switching system has to be set up to establish such kind of telephone network. Depending on the requirements and the cost, choosing the right system is very important.

PBX vs Centrex

The main difference between PBX and Centrex is that PBX is a localized telephone system, where the hardware including the switching board, the telephone wires, and the individual telephone piece is owned by the company using the system. Centrex on the other hand is a service provided by the telephone company, which tries to simulate the PBX model.

In PBX systems, the hardware required to establish a telephone network, such as the telephone wires, switchboard, receivers, and other equipment is completely and entirely owned by the company that is implementing the system. Thus the company does not have to pay any telephone service provider to establish a network within the company.

A Centrex system on the other hand is a service provided by a telephone company that tries to simulate the PBX model. Thus in this system, the telephone network and the hardware are all laid out by the telephone service provider, but the operation of the network is a complete replication of the PBX model.

Comparison Table Between PBX and Centrex

Parameters of ComparisonPBXCentrex
DefinitionIt is an independent telephonic communication systemIt is a service provided by a telephone company
Hardware InstallationHardware installation is done by the company using the systemHardware installation is provided by the telephone company
Switching centerA dedicated switch operation center is established within the company The switching center is maintained by the telephone company
Outside ExtensionsExtensions to different locations outside the office are not possibleExtensions to different locations are possible
ChargesRelatively less expensive as the system is completely maintained within the office Telephone companies often charge more for such services

What is PBX?

PBX is a completely independent telephone network is that laid out by a company to establish telephonic communication within the premises of the company. It is an independent network and no telephone provider is involved. In such a network, the hardware required for establishing the network is installed by the company. These include the telephone cables, switchboard, individual receivers, and other miscellaneous equipment.

As there is no telephone company involved in the operation, a dedicated switchboard room has to be set up within the office space, with professional switchboard operators to maintain the telephone system. The advantage of using such a system is that as t is completely independent, the set-up and installation cost is completely in the hands of the company.

But for proper functioning and maintenance of the system, professional individuals with experience in operating a switchboard as well as maintaining a telephone network are required. Hence this might add up in the maintenance expenditure. The main drawback of using this system is that since the network is completely localized within the company premises, extensions to different locations are not possible as there is no connection between the PBX network and the outside regional telephone line. Hence making phone calls to locations outside the company can be a problem.

What is Centrex?

Centrex is a telephonic communication service provided by a telephone company that tries to mimic the PBX system in its operation. As it is a service provided by a private telephone company, the telephone network is completely maintained by the service provider. Thus the installation is also under the control of the service provider.

The installation includes the set-up of all the necessary equipment for a telephone network. The phone cable is laid out by the service provider, with a switching board that is located at the service provider’s establishment. Along with this, the individual telephone receivers are also provided by the service provider. Hence the company opting for such a service does not have to purchase any hardware essential for the telephone network.

The only drawback with this system is that as the installation and maintenance of the telephone network are provided by the service provider, it is usually more expensive than the PBX system. But once the network has been set up, the operation of the network is a complete replication of the PBX system. Each telephone piece is connected to the other pieces on a completely private network inside the office space. The benefit of this system over PBX is that as the operation is maintained by a private service provider, extensions to different locations are possible.

Main Differences Between PBX and Centrex

  1. PBX is a completely independent telephonic communication network. Centrex is a service provided by a telephone company which tries to mimic the PBX model.
  2. In PBX system, the hardware installation is done by the company using the system. In Centrex service, all the hardware installation is provided by the service provider.
  3. For PBX system, a dedicated switch operation room has to be established within the company. In Centrex service, the switching operation is covered by the service provider.
  4. In PBX system, extensions to locations outside the office space of the PBX architecture are not possible. In Centrex service, extensions to locations outside the office space are possible.
  5. PBX is relatively less expensive but proper maintenance of the system is necessary. Centrex services are more expensive as the entire system is provided by a private company.

Conclusion

The telephone network for a corporate office has a slightly different operation than a regular regional telephone network.

As the calls have to be made within the office space and in the least amount of time as possible, switching time has to be as short as possible.

Hence dedicated telephone networks are laid out inside the office space for making connecting people and departments. Both PBX and Centrex are examples of such telephonic networks.

PBX is a completely private and independent telephone network, operated entirely by the staff of the company.

On the other hand, Centrex is a service provided by a private telephone company that works exactly like the PBX system.  

References

  1. https://onlinelibrary.wiley.com/doi/abs/10.1002/j.1538-7305.1971.tb01873.x
  2. https://ieeexplore.ieee.org/abstract/document/1094509/
  3. https://ieeexplore.ieee.org/abstract/document/6592593/
  4. https://ieeexplore.ieee.org/abstract/document/6541818/

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