Systems : Computer Telephony Integration (CTI)

Systems
The different types of systems used in private telephone networks include key telephone systems (KTS), private branch exchange (PBX), Centrex, and computer telephony integration (CTI). Key telephone and PBX systems often use proprietary specifications. There are several industry standards that are used for computer telephony and LAN telephony system.

Computer Telephony Integration (CTI)
CTI is the integration of computer processing systems with telephone technology. Computer telephony provides PBX functions along with advanced call processing and information access services. These services include, pre-paid telephony access control, interactive voice response (IVR), call center management, and private PBX.

CTI uses a system of interfaces between telephone switching systems (typically PBX’s) and computer systems. It is through these interfaces that information is exchanged that causes actions by the receiving system in coordination with the sender. These industry standard interfaces include telephone application programming interface (TAPI), telephony services application programming interface (TSAPI), and Java TAPI (JTAPI).

Telephony API (or TAPI) is a standard for communication between computer systems and telephone systems. Most telephone PBX manufactures provide TAPI via special interface cards that directly network with computer systems. TSAPI is a software communication standard developed primarily by the companies Lucent and Novell to allow PBX or Centrex systems to communicate through the use of NetWare communications software. JTAPI is a software communication standard based on Java programming language that allows computers to control PBX systems using Java programming language. Through the use of these standard interfaces, IVR and ACD systems can exchange information with PBX and CTI systems.

At the core of most CTI systems is a voice board installed in a Unix or Windows based computer system. The voice board is a small switch that contains line interfaces. One of the voice board line interfaces connect to a trunk line (such as a T1 or E1 line). Voice boards usually have multiple telephone extension line interfaces. These line interfaces can be for analog or digital telephones. A single CTI computer may contain multiple voice boards or expansion assemblies may be connected CTI systems can use standard or advanced digital telephones.

CTI systems can hold several software programs that are capable of different applications such as voice mail, IVR, ACD, fax, and email broadcast. CTI systems can use hard disk memory to store voice mail and fax mailboxes.

Figure 1 shows a sample CTI system computer that contains a voice card. This voice card is connected to a multiple channel T1 line. The voice card connects digital PBX stations through the voice card to individual DS0 channels on the T1 line when calls are in progress. Several software programs are installed on this system that provide for call processing, IVR, ACD, voice mail, fax, and email broadcasting. The monitor shows a directory of extensions. The advanced call processing feature shows text names along with the individual extensions to allow callers to automatically search through a company’s directory without the need to use an operator.


Figure 1: Computer Telephony Integration (CTI)