A dialogic card acts as an interface between analog telephone signals and the peripheral component interconnect bus, or PCI bus, found in computers. Buses within a computer act as channels connecting different components. The dialogic card handles information from analog phone lines and are used in applications such as voice messaging, notification systems, auto dialers, and voice mail. They are also used for interactive voice response, automatic call distribution, and voice or audio response systems. Used in many voice recording products, dialogic cards are produced in both digital and analog configurations depending on the way they are utilized.
Allowing high-density applications, dialogic cards are mostly used in automated telephone systems with services such as predictive dialing and conferencing. There are cards that can handle a number of phone calls simultaneously. A dialogic card can even route each call to the correct representative. The core function of a dialogic card is to integrate computers with telephones, enabling a wide variety of functions. The internal distributed bus switching allows rerouting of both inbound and outbound calls.
Voice decoding and encoding, retrieving caller ID numbers, and making and answering calls are all made possible through a dialogic card. It can detect the touch tones dialed, record sounds from the phone line, and identify when the connection has been severed. Most of the cards can handle many analog lines and have protection circuitry on board that makes them very reliable. Certain signaling functions, like current detection, can not only be monitored but also controlled through the computer with the help of a dialogic card. It's also possible to configure multiple boards within a single chassis and expand the number of analog ports easily if necessary.
Earlier applications for dialogic cards were written with telephony application programming interfaces or APIs, like Dialogic R4, GlobalCall, and ECTF S.100. ActiveX controls like visual voice and Java-based APIs, including API and JTAPI, were also used to create telephony applications. They all, however, had numerous issues. The Java-based APIs are no longer utilized, and the ECTF S.100 is used very rarely. Other proprietary scripting languages have also been abandoned over time.
All these APIs were constrained to very specific operating systems and were not widely adopted as standards. They all fell into disuse as more modern, web-based standards evolved. Two widely used telephony standards that became popular over time were VoiceXML and CCXML. They have the added advantage of being based on the ubiquitous XML and HTTP, making them easier-to-use web-based technologies.