ISO 8583 is an international standard for financial transaction card originated interchange messaging.
ISO 8583 defines a message format and a communication flow so that different systems can exchange these transaction requests and responses.
The ISO 8583 specification has three parts: A card-based transaction typically travels from a transaction-acquiring device, such as a point-of-sale terminal (POS) or an automated teller machine (ATM), through a series of networks, to a card issuing system for authorization against the card holder's account.
Based on this information, the card issuing system will either authorize or decline the transaction and generate a response message which must be delivered back to the terminal within a predefined time period.
Cardholder-originated transactions include purchase, withdrawal, deposit, refund, reversal, balance inquiry, payments and inter-account transfers.
ISO 8583 also defines system-to-system messages for secure key exchanges, reconciliation of totals, and other administrative purposes.
Bearing each of the above four positions in mind, an MTI will completely specify what a message should do, and how it is to be transmitted around the network.
Each data element is described in a standard format which defines the permitted content of the field (numeric, binary, etc.)
Transaction can be sent again in a few minutes) The point of service (POS) mode field state what conditions the card has been read under, which type of authentication has been made, and depending on the version of the specification, what the capabilities of the terminal are.
The Australian standard AS 2805 incorporates ISO 8583 and also covers a large number of other payments topics.