IP Centrex is the Central Office Exchange Services (Centrex) for enterprises based on the IP telephony technologies. The traditional Central office exchange service (Centrex) is a telephone switch service used by enterprises in which switching occurs at a central (local) office . In traditional Centrex service (i.e., analog Centrex and ISDN Centrex), call control and service logic reside in a Class 5 switch located in the Central Office. The Class 5 switch is also responsibility for transporting and switching the electrical signals that carry the callers' speech or other information (e.g., faxes).
In IP telephony, voice conversations can be digitized and packetized for transmission across the network. IP Centrex refers to a number of IP telephony solutions where Centrex service is offered to a customer who transmits its voice calls to the network as packetized streams across a broadband access facility.
- IP Centrex has the following key benefits:
- Increases utilization of access capacity
- Provides all the calling features and call control capabilities available today for Analog Centrex and ISDN Centrex services.
- Allows the customer to combine its existing solutions for data and telephone service into a consolidated network.
- Provides Multilocation Centrex with the ability to make two or more locations part of the same Centrex group. With IP Centrex, geographic location is not a factor when defining a Centrex group.
- Promotes Computer Telephony Integration (CTI) and Softphones solutions where telephone functions can be controlled by the user's PC, and where telephone information (e.g., caller id information) can be integrated with other software applications.
- With IP Centrex, certain Move, Add, and Change (MAC) activities can be eliminated when a user (of an IP Phone) changes offices. The phone number and features follow the IP Phone throughout the LAN, without needing any change orders.
- IP Centrex is fully compatible with previous Centrex services. Analog lines, ISDN lines, and IP Centrex lines can all be made part of the same Centrex group.
Currently there two major IP Centrex architectures. One utilizes the class 5 switch as the call control and switching and adds the IP Centrex network and customer gateways to provide the IP functions. The other uses the software switch for call control and signaling and switching is also packetized using ATM or IP switches.
IP Centrex: IP telephony based Central Office Exchange Service - 1
IP Centrex: IP telephony based Central Office Exchange Service - 2
Related Terms：PBX, IP Telephony, Centrex, Class 5 switch
Reference Links：http://www.ip-centrex.org/: IP Centrex