The early 1960s saw the breakthrough in telecom technology with the innovation of Centrex by the Engineering Department of New York Telephone (NYTel) which led to the swapping of PBX switchboards of large customers. The Centrex service is basically the outsourcing of in-house enterprise telephony services to an outside service provider. Generally, the telephony services comprise of toll-free calls inside the organization, extension calling, toll-free calls linking different branches of the organization; voice mail, basic call center; and conferencing. Centrex is a very vital part of most ventures as they need to outsource a great deal of services and processes that has nothing to do with the core business. In the absence of such a system enterprises have to buy, set up and manage all the paraphernalia required to facilitate the services like toll free calls, voice mail servers, and such others.
In spite of the fact that Centrex is not the core business most businesses consider telephone services as an indispensable part of business necessary for running of all business operations in a smooth manner. The investment in capital equipment which is vital for telephony services and the trained employees and process cost which is accrued in maintaining such a set up is saved to a great extent. In the world of IPCentrex, to be able to supply the service, all that one requires is a speedy IP connection to the customer. This can be performed on another service provider’s network, employing an IP-VPN service or even the public Internet.
In the IP world, the IP-PBX, the phones, the PSTN connections and the value-adding application servers can be positioned in any place on the IP network. So, IP Centrex service can be executed in various ways. The IP-PBX can be placed in the customer site, co-located in the service provider site, or executed as a divider on the service provider IP Centrex server. It is the same with the value-adding application servers. The service provider can administer the service distantly for the enterprise free from the location of the system in every case.
Initially, Centrex service implied combining various regular PSTN lines under one head providing toll-free calls within the organization, dial plans for different Centrex customers, and basic value-added services through the PSTN TDM system. Apart from this, Centrex customers were guaranteed of certain benefits like dependable and worriless service, maintenance, and improvements, and avoiding unused floor-space owing to on-site PBXs.
An enterprise PBX solution is incomplete in the absence of value added services. The Centrex model offers the enterprise an enormous benefit. Rather than having to buy, organize, and maintain very complex systems on their own, customers are able to enjoy the economies of scale of a service provider, which gives service together with a system supporting many customers. IP Centrex in fact generates a fresh business model and a new type of service provider.