Key Telephone System


A Key Telephone System (KTS) is a communication system predominantly used in businesses, which allows multiple telephones to share a certain number of outside lines for making telephone calls. The “Key” in Key System refers to the functionality where a user can manually select outgoing lines and incoming calls at the press of a button (‘keys’). These systems can also offer various features such as call transferring, conference calling, and others, providing cost efficiency and flexible line selection.


The phonetic pronunciation of “Key Telephone System” is: /kiː tɛlɪfoʊn ˈsɪstəm/

Key Takeaways

Key Telephone System (KTS) is a multi-line phone system designed specifically for businesses. The following are three key points about KTS:

  1. Multiple Lines: KTS provides businesses with the capability to handle several lines across multiple phones. In such a system, there are no physical lines running to each phone. Instead, the system operates over a local network.
  2. User-Friendly: Users can easily see which lines are in use and which ones are free because each line has its own light. If someone is on a call, the light for that line will be on. This provides workers with a straightforward way to manage calls effectively.
  3. Flexibility: Many KTS units come with a variety of helpful features such as call transferring, conference calling, call holding, speed dialing, and intercom. They can also be easily upgraded or expanded as the business grows.


The Key Telephone System (KTS) is an important technology term primarily because it represents an essential communication tool used widely in businesses and offices. Unlike traditional telephone systems, a KTS allows multiple lines to be answered and utilized from a single station, improving efficiency and allowing for flexible communication structures.

Key systems generally provide features that are tailored toward businesses with requirements for handling several calls simultaneously and are often less complicated and more economical than larger Private Branch Exchange (PBX) systems. This technology is significant for its role in facilitating effective business communication, enhancing workflow, and providing scalability for growing organizations.


The Key Telephone System (KTS) is a multi-line telephone system primarily used by businesses, both small and large, due to its capacity to handle multiple calls simultaneously. This system is designed to enable multiple users to share several outside telephone lines, reducing the necessity for individual lines for each separate phone device and thereby saving costs. The system is known as ‘Key’ due to the fact that users press ‘keys’ or buttons to access different lines or features such as holding calls, transferring calls, or engaging in multi-party calls.

The primary purpose of a Key Telephone System is to facilitate efficient and effective communication within businesses and organizations. It brings about a streamlined process for handling incoming and outgoing calls, thereby improving business operations. For example, a receptionist at a company can effectively manage multiple callers, place them on hold when necessary, transfer them to the intended recipient, or organize conference calls.

Such versatility allows businesses to handle client queries effectively, liaise internal communication seamlessly, and offer exceptional service to clients, which is crucial for business reputation and growth.


1. Corporate Office Communication: Large-scale corporate offices often use Key Telephone Systems (KTS) to connect multiple telephones within the same building. This technology is used to communicate between departments, hold conference calls, and transfer calls to different areas. For example, a call may come into the reception desk and the receptionist can press a button to directly connect the call to the relevant department.

2. Hotel Communication System: In hotels, Key Telephone Systems are often used to provide communication between guest rooms and front desk staff. The system can also allow for internal communication between staff, such as housekeeping, concierge services, and management. For instance, a guest can contact the front desk directly using a one-touch button on their room telephone.

3. Medical or Healthcare Facilities: In hospitals or other healthcare facilities, a Key Telephone System can prove essential for efficient communication between doctors, nurses, administrative staff and patients. In an emergency situation, quickly being able to communicate with the exact person or department needed can quite literally be a lifesaver. For example, a nurse can quickly dial the on-call doctor’s extension using a one-touch button on their unit’s telephone.

Frequently Asked Questions(FAQ)

Q: What is a Key Telephone System (KTS)?

A: A Key Telephone System is a multi-line phone system typically used in small or midsize businesses. It allows users to manually select outgoing lines or answer specific incoming lines.

Q: How does a Key Telephone System (KTS) work?

A: The Key Telephone System works by connecting multiple telephone lines to a single unit or “key system”. Each inbound or outbound call can be directed to a specific line, making it easier for users to manage multiple communications in an efficient manner.

Q: How many lines can a Key Telephone System (KTS) handle?

A: The number of lines a Key Telephone System can handle typically varies from system to system, ranging from a few lines to dozens depending on the model and configuration.

Q: What types of businesses benefit from a Key Telephone System?

A: Small to midsize businesses with moderate call volumes typically benefit most from using a Key Telephone System. These can include businesses like retail outlets, small offices, or businesses with multiple departments.

Q: What is the difference between a Key Telephone System (KTS) and a Private Branch Exchange (PBX)?

A: The main difference is scale and functionality. While KTS is designed for smaller businesses with fewer phone lines, a PBX is designed for larger organizations that need advanced call routing options and may have hundreds of phone lines.

Q: Can a Key Telephone System (KTS) be integrated with Voice over Internet Protocol (VoIP)?

A: Yes, many modern Key Telephone Systems can be integrated with VoIP services. This can allow for greater flexibility, lower costs, and additional features like voicemail to email delivery.

Q: What are some common features of Key Telephone Systems (KTS)?

A: Common features of a Key Telephone System include call holding, call transferring, conference calling, speed dialing, and sometimes, voicemail and auto-attendant capabilities.

Q: Do I need special equipment to install a Key Telephone System (KTS)?

A: Yes, you need a Key Service Unit, which is the central unit that connects to all the phone lines and handsets. You may also need specific types of handsets that are compatible with a KTS.

Q: How are Key Telephone Systems (KTS) maintained?

A: Regular maintenance of a KTS involves checking and updating the Key Service Unit’s software, checking the telephone lines for connectivity, and troubleshooting any issues with the handsets or other connected hardware.

Related Tech Terms

  • Private Branch Exchange (PBX)
  • Central Office (CO) Lines
  • Station Equipment
  • Intercom System
  • Voicemail Integration

Sources for More Information


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