The Avaya Computer Telephony DIP installed on the Avaya IR system provides a transparent interface to Avaya Computer Telephony on the Avaya Interaction Center. It is accessed through a single external function, named Vesp_dip. Applications invoke DIP functions to communicate with the VOX Server, the entry point into the Avaya Computer Telephony environment. The VOX Server, which can communicate with both environments, interprets these functions and provides all subsequent processing required to interact with Avaya Computer Telephony.