Wikipedia
Traditionally, computer telephony integration (CTI) integrates a telecom system, IT infrastructure, and software application(s) with relevant and/or target customer data. This integration is typically difficult to use and requires a significant level of sophistication.
The primary business purpose of Universal CTI is to provide a software bridge between the various computers and telephone systems in call center environments. Applications made possible by Universal CTI include screen pop, coordinated call-data transfer between agents and interactive voice response (IVR) integration, which transfers caller-entered IVR information to agent desktop workstations. By integrating computers and telephone systems, Universal CTI applications allow call centers to realize significant advances in both agent productivity and quality of customer service. The service-oriented architecture of Universal CTI provides a WSDL (web services based) interface for agent desk top applications or self-service (IVR) applications to communicate to the CTI Server (Genesys T-Server/CISCO ICM/ Avaya AES) in a given call center.
In the commonly encountered open environment, a call center solution may consist of multiple CTI servers in disparate locations from multiple vendors running multiple applications simultaneously. Currently, in such a real-life situation, it's no longer possible to develop applications with custom interfaces to each one of these CTI servers, maintain the applications, and change applications as business requirements change without a dedicated staff to manage the various CTI interfaces.