Central Office Installation

Definition of a Central Office (CO)

A central office is a building in which business lines are connected on a local loop. This office has telephone switches to switch calls locally or to a long distance carrier office.

Local telephone trunks converge through an intricate system of switching equipment, where each call connects to its destination electronically.

All of the twisted-pairs of cables are run from the cable vault where they meet the main distribution frames (MDF) as well as fiber cables which meet their equivalent optical distribution frame (ODF).

An optical distribution frame (ODF) is a frame used to provide cable interconnections between communication facilities. Fiber splicing, termination, adapters and connectors are connected together within a single unit. This protects fiber optic connections from damage.

The amount of wiring is quite incredible. All the wires are spread out across a vast latticework of steel racks.

The switch is the brains of the telecommunications central office. It is a large computer which simply switches circuits around for the phone connections that are established and fed to the building.

Uptime, network integrity, equipment compatibility, and natural disaster survivability are of major importance for the equipment that is installed. 

Thousands of pairs of cables are fed from the streets and enter the Central Office through thick concrete bulkheads, into a lower level chamber or vault. The cables are twisted together in pairs to make each phone circuit different.

Internal pressure is used in the cables to keep water and other materials out to prevent damage. All the cables are grounded to avoid damage from lightning or other electrical surges.

Cables are run along the walls of the vault in steel racks to keep everything tidy.

A central office installation professional performs installation, maintenance, and repairs of central office equipment. Preventive maintenance and service activation / deactivation of office equipment is involved.

Technologies include:

  • Digital microwave radios
  • FOTS
  • Subscriber carrier
  • Digital multiplex
  • Switching
  • Frame Relay
  • Intelligent channel Banks
  • DACS
  • IP
  • Power
  • Cross connection
  • Miscellaneous equipment

These professionals use manual and power tools safely and efficiently to perform installations and repairs. Testing and labeling of cable lines is performed. Cable management in telecommunication rooms and equipment stations is required.

Identification and troubleshooting of equipment problems sometimes arise in a Central Office Installation. Documentation for all installations, maintenance, repairs, and inspections help future technicians find the information needed.

Equipment frames need to be assembled, cable racks and other auxiliary equipment frames as well. There are standard wiring color codes and strips that need to be adhered to for inspections to pass.


Central offices can experience a vast array of equipment needs or issues throughout their existence. New COs require a well thought out design and plan in many disciplines, AC/DC power, HVAC, fire suppression etc. The design work will set the stage for many years to come, and it is imperative that it is well planned from the beginning. 

More commonly central office installations occur in existing offices as expansions to existing equipment or new technologies replacing the older legacy equipment. Working in an active CO requires that all technicians are trained and understand the severity of their actions. Many issues can arise in an existing office whether it be improper installation in the past or simply the room is running out of space or available power. 


Commerx has over 25 years of experience working in COs and performing just about every type of service available. We can design your new CO and provide the personnel to perform the equipment installation as a turn-key solution. 

We can assist carriers with their required network expansion as we have experience with many OEMs installation procedures and methods. We are experts in line grooming and legacy switch consolidation leveraging our inhouse proprietary migration software and collaboration tools. In a nutshell, we have you covered for your central office needs.

How Commerx Can Help Your Business

Commerx can help your business with Central Office Installations so you can focus on your primary business functions.