Skip Ribbon Commands
Skip to main content



Category: Telecom

​Centrex is a central office-based telecommunications system owned by an outside service provider. It typically provides an agency direct dial numbers per user and does not require on-site common control equipment such as an Electronic Key System (EKS) or Public Branch Exchange (PBX). Centrex allows for easy unification of multiple sites in a centralized area by providing a common abbreviated dialing plan that can be used to dial between any two telephones that are in Centrex. Centrex provides a basic feature set and is usually delivered via analog access lines with digital lines available for larger sites. It also includes access to local and long distance calling as well as voice messaging.
Centrex system allows incoming calls to be dialed direct without the assistance of an operator. Centrex equipment is located at the local telephone company's central office premises and every telephone served by the Centrex system is directly connected to the telephone company switching center. A Centrex system offers many different features for telephone users.

Centrex systems are available at various locations in the state. The most familiar Centrex systems are in Springfield (Area code 217/Prefixes 524, 557, 558, 782, 785, and 786) and Chicago (Area code 312/Prefixes 338, 793, 814). Please contact your Communications System Specialist (CSS) for additional information on Centrex systems throughout the state.

The telecommunications services of the Bureau of Communications and Computer Services (BCCS) are available to all Illinois State agencies, boards, commissions, universities, Offices of the Illinois House and Senate, and Constitutional Officers.


Centrex - AT &T

Shared Services  Unit of Measure  Service Rate
Analog or Digital Line Service​ ​$ 60.50
​Phantom Line Service (Prerequisite - Digital Line) ​$  5.25
Misc. Carrier Charges Per Minute 110% of Vendor Rates
Analog Line Service Per Line $ 14.00
Digital Line Service Per Line $ 16.00
Phantom Line Service​ ​Per Line ​$    .25


Shared Services  Unit of Measure  Service Rate
Install Per Line

$ 13.20

Line Charge $ 22.00

What is Included?

Standard Features

  • Programming Standard programming on telephone lines includes a one-time programming charge to make the appropriate changes in the telephone switch. An additional fee is charged for programming to proprietary telephones (P-Phones) because of their complexity. Agencies can eliminate many charges by obtaining access to AT&T CentrexMate to enter their own programming changes. CMS staff provides CentrexMate training for authorized agency Telecommunications Coordinators.

Basic Feature Package
The Basic Centrex Feature Package is available on all new and existing lines. The basic feature package is available in primary Springfield (Area code 217/Prefixes 524, 557, 558, 782, 785, and 786) and Chicago (Area code 312/Prefixes 338, 793 and 814) central offices. The package may also be available in other areas of the state where central office equipment permits. Unless otherwise specified, your telephone line will automatically be upgraded to the basic feature package when any programming is requested on the line.

The basic feature package includes the following:

  1. Call Forwarding Variable: Calls automatically forwarded to another number
  2. Consultation Hold: Put a call to another telephone
  3. Call Transfer: Transfer a call to another telephone
  4. Three-Way Calling: Add a third caller to an existing conference call
  5. Call Park: Call can be received at any telephone within the Centrex system using code
  6. Last Number Redial: Automatically dial last number called
  7. Speed Calling (Individual): Quickly access specific regularly-called numbers without having to dial the complete number
  8. Conference Call (6 Parties): Conference call with up to 5 other callers
  9. Ring Again (Auto Call Back): Allows a called busy line to call you back when free.

For information on Audio Conferencing options please click here.

Please click here for User Instructions related to Basic Features.

  • Station Dial Conference Calling: (6 Participants- or less) "FREE" feature available on phones in Springfield, Collinsville, and Chicago/Franklin Centrex (773, 814, or 872 Area Codes.) For Station Dial Conference Calling Instructions

    The host direct-dials to connect up to five land and/or cell phones. If calling and connecting to parties also on Centrex, there is absolutely no charge for any connections. If calling local exchanges outside Centrex or any long distance numbers, the host will pay only the applicable local calling rate and/or applicable long distance rate for each participant.

Programmable Features

Programmable features are available with a one-time programming charge per telephone or line, no monthly charge.  Agencies can eliminate many charges by obtaining access to AT&T CentrexMate to enter their own programming changes.  CMS staff provides CentrexMat training for authorized agency Telecommunicatins Coordinators. 

  1. Call Forwarding Don't Answer / Call Forwarding Busy (CFA / CFB): Call is forwarded if line is not answered after set number of rings or is busy
  2. Call Pickup: Call can be answered at any telephone within a pickup group with an abbreviated code rather than entering the complete extension
  3. Hunting: Call is routed among a group of lines in a designated order for up to 5 lines. Special provisions would be needed if more than 5 lines would be used
  4. Speed Calling:
    1. Group of 30 Numbers: Like the standard Speed Calling feature with the additional capability of programming up to 30 regularly-called numbers.
    2. Group of 50 Numbers: Like the standard Speed Calling feature with the additional capability of programming up to 50 regularly-called numbers.
    3. Group of 70 Numbers: Like the standard Speed Calling feature with the additional capability of programming up to 70 regularly-called numbers.
  5. Call Waiting / Cancel Call Waiting: User is notified by tone during an existing call that another call has been received and is on hold. Feature can be cancelled with designated code
  6. Denied Originating Service: No outgoing calls can be sent although incoming calls can be received
  7. Denied Terminating Service: No incoming calls can be received although outgoing calls can be sent
  8. Restricted Line: Designated types of outgoing calls are restricted (i.e., long distance, interstate, foreign, etc.)
  9. Directed Call Pickup (No Barge-In): Activation code sends calls to a designated line in customer group to be answered
  10. Directed Call Pickup (Barge-In): User dialing activation code can be included in call directed to and answered at a designated line in customer group
  11. Direct Connect: Direct connection of telephone from one station to another
  12. Call Forwarding Variable / Outside: Telephone calls can be automatically forwarded to a number outside the Centrex system.

Extra Feature

Extra feature is available for a one time install charge per telephone or telephone line.

  1. Caller Identification (Caller ID): Displays the number of the call being received. Catalog Code: SSCIX

Please click here for User Instructions related to Programmable Features.

Requests for non-standard services should be directed to the Customer Service Center (CSC) at the number listed below.

What Should You Expect?

  • Access to the State of Illinois Long Distance Network Service
  • Lower installation costs and space savings
  • Growth potential with accessibility to multiple locations
  • Fewer system operators
  • 4 or 5-digit dialing within Centrex and additional user features
  • Maintenance performed by the telephone company
  • Please contact your CSS for installation estimates and planning
  • Installation by mutually agreed upon due dates
  • Ordering tasks are performed during regular business hours, Monday through Friday, 8 a.m. to 5 p.m.
  • CSC Communications Systems Specialists (CSS) are dedicated to providing price quotations and low-cost alternatives, clarifying order information, monitoring order status, and updating billing information. They also help with the analysis and development of the appropriate product and service mix to fulfill specific short and long term customer needs
  • Integrated ordering, inventory, and billing in a shared database that's accessible to customer Telecom Coordinators to enable service order tracking, usage reporting and billing review. Customer Telecom Coordinators also receive automatic Service Bulletins announcing changes in equipment offerings, price, and procurement procedures.
  • Automated agency billing - included in monthly call detail provided by CMS Business Services
  • Detailed trouble tickets documenting repair/maintenance issues through to successful resolution
  • Coordination of training in the efficient use of products and services
  • Notification of manufacturer discontinued equipment

How Can You Help?

  • Routine review of billing for errors and underutilized service and equipment
  • Consult agency's assigned Communications System Specialist (CSS) for suggested low-cost alternatives
  • Routine review of added special features
  • Provide a designated agency contact and related contact information for BCCS to interface with when needed