A POS is a functional device that has its own dedicated software and is customized according to the authorization system of the bank it is connected to, and that accepts credit or debit cards.
For a bank to be able to provide a POS to its customers, the authorization system and the POS message structure must be coded according to the ISO 8583 standard and be compatible with each other.
For example, when a transaction is started on the POS by entering the Sale menu and entering the transaction amount, the POS sends the following to the authorization system;
- Card Number in field F2,
- Transaction Amount in field F4,
- Currency in field F49 (949 is sent for TRY transactions), etc. The authorization system also knows that this information will be sent in the fields specified above. Accordingly, the necessary checks are performed in the bank's system and the transaction is approved or declined.
So, is it enough for the integration between the POS and the POS bank to be established just once?
Once the general flow has been agreed upon, for every new function added to the POS, the POS bank and the POS software must mutually agree again and develop accordingly. The technical document covering what will be done between the POS bank and the company that develops the POS software is called the Spec document. Development generally does not begin before the Spec document has been prepared.
