What are the PVX, ACD and IVR in call center set up?

Hello

Interactive Voice Response (IVR) is an automated telephony system that interacts with callers, gathers information and routes calls to the appropriate recipient. An IVR system (IVRS) accepts a combination of voice telephone input and touch-tone keypad selection and provides appropriate responses in the form of voice, fax, callback, e-mail and perhaps other media.
ACD - Automatic Call Distributor :-A phone system that performs four basic functions: answers incoming calls, gets information and instructions from database, determines the best way to handle the call, and sends the call to the proper agent, as soon as one is available.