The main objective of this system is used to create an interface for switching messages between switch and core banking server (CBS) at the bank, basically where it works on request response system using ISO-8583. ASI consists of functionalities such as balance enquiry, POS and reversal. Whenever the customer requests for any of the above functionalities from their CBS account through ATM, switch sends the request to CBS Host in turn CBS Host replies with successful response for the transaction or declined response. When customer request for balance enquiry or POS transaction, the request is passed to switch and switch transfers the request in bit-string and that string is divided into three parts which includes Message Type Indicators, Bitmaps and Data elements. Based on MTI, transaction request type can be identified whether it is financial request or reversal request. Bitmaps indicates which data elements are present in the request. Data elements are the fields which con