Consulting on the installation of internal switchboard systems
A switchboard system includes:
- Telephone switchboard: central unit specializing in processing and switching all calls, conversation signals, digital signals…
- Trunk line (postal line from public telephone network provider)
- Extensions: includes all desk phones, mother-in-law phones, printers, fax machines…
- Cable box: where signal wires are concentrated, used to connect terminal devices… to prevent lightning and make future warranty and maintenance simpler.
Additional accessories of the switchboard include:
- Backup power supply: The backup power supply will connect directly to the switchboard in case of a power outage, ensuring the operation of the switchboard during a power outage.
- DSS monitoring desk: Identify the status of extensions in the system (hang up, busy, busy trunk, free trunk…)
- Displaying the incoming call number (CID) has 3 types depending on the switchboard line we are using
- Integrated switchboard. It was displayed directly on desk phones (with screens).
- The incoming call number display box is independent of the attached switchboard.
- Card displaying the incoming call number: reserved for switchboard lines that are not built-in and must be upgraded separately

Internal switchboard connection diagram:
- On the switchboard, there will be many ports that we collectively call ports.
- Ports to connect to external lines are called trunk lines (CO).
- Ports to connect internal devices are called extensions (EXT)
- On the switchboard, there will be 1 COM port – to connect to the computer that manages the entire system.
- Battery connection port.
- All devices in the switchboard are connected by 2P or 4P telephone wires. Usually, 1 wire has 2 conductors: cool wire and hot wire.

Operation of internal switchboard
When receiving a call signal from outside (trunk line), the switchboard will receive and process that call. There are 2 ways to program the switchboard as follows:
- Direct ringing: there will be a regulation to ring a specific direct extension. The person on the phone needs to pick up and talk to the customer.
- DISA mode: The switchboard will automatically issue a greeting message instructing the customer to operate right on the customer’s phone to meet the department they wish to meet. Within 10 seconds, if the customer does not take action, the switchboard will automatically ring on the extension that we have specified.
- Each branch of the switchboard is assigned a certain number that we program for it on the ports of the switchboard.
Security and management capabilities:
- The switchboard sets up a password for each extension. When calling outside the switchboard, you are required to enter a Password to be allowed to call out.
- Regulations that each trunk is allowed to call mobile, intra-city, inter-province…