Computer telephone integration (CTI) is technology that lets computer systems interact with telephones. These applications are often used in call centers, and allow companies to log, track and record calls for quality assurance and marketing purposes. Most CTI vendors use one of several technical standards, and private branch exchanges (PBX) as well as integrated services digital network (ISDN) manufacturers, and adopt these benchmarks before they release telephony products onto the market.

What are CTI Standards?

CTI standards are application programming interfaces (APIs) and call control models that let computer users receive voice calls over the internet. These standards have helped normalize the computer telephony industry, and are used by PBX and ISDN manufacturers. CTI standards define the protocol used to connect a computer with a telephone, so users can communicate with each other via a secure, stable network.

Here are some popular CTI standards:


Computer-supported telecommunications applications (CSTA) is one of the most common CTI standards. It is approved by the International Telecommunication Union (ITU) — a CTI standards body and the agency of the United Nations responsible for information and communication technologies. A wide range of industries, such as healthcare management and retail, use CSTA standards.

CSTA is a protocol that supports the structure of a CTI system and its features, such as call forwarding and conferencing calls. Specifically, it facilitates the data messages that control CTI applications. CSTA allows users to make phone calls from their computer and access information — contact details, previous interactions, product histories, etc. — about customers and clients from one centralized dashboard.

CSTA works like this: when a user receives a phone call, a message is sent from a telephone exchange to their computer. This message includes information about the caller — their area code and phone number, for example — and the number they dialed. Then, the computer locates the caller’s profile from a database and presents this information to the user. This entire process is automated.

Think of CTSA as the glue that holds a CTI system together. CSTA messages can be transmitted in a number of different ways. Data is sent through an integrated services digital network (ISDN), for example, or a TCP/IP network.


The Java Telephony Application Programming Interface (JTAPI) is a call control model that has been developed by Sun Microsystems. Just like CTSA, JTAPI supports the transfer of data between a computer and a telephone and is often used in large call centers.

JTAPI was designed by computer and telecommunications companies — Intel, Novell, Sun Microsystems, etc. — to compliment existing CTI platforms and integrate first-party and third-party call control models. The first version of this application was released in 1997.

JTAPI serves multiple functions. The application manages CTI route points so users can distribute incoming calls to the right person. It also supports the software that generates real-time call analytics. Users can discover the number of calls received at a particular time of the day, for example, or which phone agent received the most calls. The Java telephony API is commonly used in the healthcare and hospitality industries, too. More companies are investing in this type of CTI integration.


The Telephony Application Programming Interface (TAPI) is a CTI standard developed by Microsoft and introduced in 1993. Like CSTA and JTAPI, this application is used to expedite call center management. TAPI transfers data from a computer system to a telephone, and users can access caller information with a click of a button.

When a user’s computer has TAPI and the right hardware, he or she can receive voice calls over the internet. TAPI functions include call dialing, call holding, and call forwarding. Users can also add notes to a caller’s profile, record calls, arrange conference calls, send and receive fax messages, as well as program their computers to receive calls from certain numbers automatically.

In a call center context, TAPI allows phone agents to capture data — a person’s name, address, email address, etc. — during a phone call. This information proves useful for call centers that want to engage with their customers and provide them with personalized services.

Data collection promotes better decision-making and problem-solving. It streamlines sales prospecting, too. Marketers can collect valuable information about callers and then move these prospects through the sales funnel. All of this is made possible with TAPI implementation.


The Telephony Server Application Programming Interface, (TSAPI), is a CTI standard developed by Novell and AT&T. It allows users to track and record calls using NetWare servers. TSAPI differs from Microsoft’s TAPI. It is a server-based system that doesn’t run on an operating system.

TSAPI runs with clients such as Novell NetWare, Microsoft Windows 95 and NT, IBM OS/2, Unixware and Apple Macintosh. It was created during a time when wide area networks (WAN) were popular. Many PBX manufacturers supported the technology; however, the cost of developing drivers was high.

TSAPI benefits companies that want to communicate with customers and clients more effectively. This technology provides users with detailed caller profiles that contain useful information for marketing, sales and customer service. TSAPI enhances collaboration between various departments within the workplace, too. Data collected from a TSAPI-support computer-telephone system can be shared between teams and used to make forecasts about future business activities.


Device Media Call Control (DMCC) is an API that lets companies record phone calls from Avaya’s Communication Manager. The API provides users with an effective telephony solution. It helps them improve customer service and reduce operating costs, and requires no hardware. DMCC was formerly known as the Communication Manager Application Program Interface (CMAPI).

DMCC’s call control feature is supported by TSAPI and aids third-party control capabilities. Other features include call transfers and conference calls. Call center managers use this software to monitor customer complaints and track call trends. Call data is displayed on a simplified dashboard, making it easier for users to access information.

DMCC is a powerful tool that measures productivity, as well. Call center managers can record calls for quality assurance purposes and discover which agents provide callers with the best service. The latest version of the software was released in May 2016. TDM, IP, and hybrid telephony environments are among the various recording methods available.


CSTA, JTAPI, TAPI, TSAPI and DMCC ensure that a CTI operates properly. These standards ensure the smooth transfer of data from a computer to a telephone, and vice versa. Not all CTI systems support this technology, though. PBX and ISDN manufacturers need to write specific drivers for each of these standards — something that takes both time and money.

Read More: What is a CTI Server?