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Computer Telephony Integration (CTI)

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Computer telephony integration (CTI) is a technology that allows interactions on a telephone and a computer to be integrated or co-ordinated. As contact channels have expanded from voice to include email, web, and fax, the definition of CTI has expanded to include the integration of all customer contact channels (voice, email, web, fax, etc.) with computer systems.


Common functions

The following functions can be implemented using CTI:

  • Call information display (caller's number (Automatic number identification), number dialed (DNIS), and Screen population on answer, with or without using calling line data
  • Automatic dialing and computer controlled dialing (fast dial, preview, and predictive dialer|predictive dial.)
  • Phone control. (answer, hang up, hold, conference, etc.)
  • Coordinated phone and data transfers between two parties (i.e., pass on the Screen pop with the call)
  • Call center phone control. (logging on; after-call work notification)
  • Advanced functions such as call routing, reporting functions, automation of desktop activities, and multi-channel blending of phone, e-mail, and web requests
  • Agent state control (for example, after-call work for a set duration, then automatic change to the ready state)

Forms of CTI

Generally, there are two forms of CTI.

  • First-party call control
    • First party call control operates as if there is a direct connection between the user's computer and the phone set. An example of this would be a modem card in a desktop computer, or a phone plugged directly into the computer. Typically, only the computer associated with the phone can control it, by sending command directly to the phone. The computer can control all the functions of the phone, normally at the computer user's direction. First party call control is the easiest to implement but is not suited to large scale applications such as call centers.
  • Third-party call control
    • Third-party call control is more difficult to implement and often requires a dedicated telephony server to interface between the telephone network and the computer network. Third party call control works by sending commands from a user's computer to a telephony server, which in turn controls the phone centrally. Specifically, the user's computer has no direct connection to the phone set, which is actually controlled by an external device. Information about a phone call can be displayed on the corresponding computer workstation's screen while instructions to control the phone can be sent from the computer to the telephone network. Any computer in the network has the potential to control any phone in the telephone system. The phone does not need to be attached directly to the user's computer, although it may physically be integrated into the computer (such as a Voice over Internet Protocol soft phone), requiring only a microphone and headset in the circuit, without even a keypad, to connect to the telephone network.

CTI application event flow

A typical CTI application manages the event flow that is generated by the telephony switch during the life cycle of a call. This typically proceeds along the following sequence:

  • Set up
  • Deliver (ringing)
  • Establish (answer)
  • Clear (hang up)
  • End

Other call events that can be handled by a typical CTI solution include the following:

  • Hold
  • Retrieve from hold
  • Conference
  • Transfer
  • Forward

CTI applications handle events related to ACD (automated call distribution) such as:

  • Agent logged in
  • Agent available
  • Agent not available
  • Agent ready
  • Agent not ready


The origins of CTI can be found in simple Screen Population (or "Screen Pop") technology. This allows data collected from the telephone systems to be used as input data to query databases with customer information and populate that data instantaneously in the customer service representative screen. The net effect is the agent already has the required screen on his/her terminal before speaking with the customer.

This technology started gaining widespread adoption in markets like North America and UK/Northern European countries.

There were several standards which had a major impact in the ┬┤normalization┬┤ of in the industry, previously fully closed and proprietary to each ACD vendor. On the software level, the most adopted interface by vendors is the CSTA standard, which is approved by the standards-body ITU. Other well known CTI standards in the industry are JTAPI, TSAPI and TAPI: JTAPI, the Java Telephony API is promoted by Sun; TSAPI, originally promoted by the AT&T (later Lucent then Avaya) and Novell, by far the most adopted in large scale contact centers; Microsoft pushed their own initiative also, and thus TAPI was born, with support mostly from Windows applications.

CTI Vendors