Author
Payment systems expert and technology executive
Arif Ünal is a technology executive with more than 20 years of experience in banking, fintech and payment systems. He writes about card payments (issuing and acquiring), POS, ATM, e-money, FAST and Turkish payments regulation (BRSA and CBRT). He has held senior roles at Finagotech and managed payment systems and digital banking teams at Emlak Katılım, Vakıf Katılım and Türkiye Finans. He holds a B.Sc. in Industrial Engineering from Istanbul University and an M.Sc. in Management Information Systems from Marmara University.
976 articles
Credit Card
PSE (Payment System Environment) is a directory on the card named 1PAY.SYS.DDF01 for a contact chip and 2PAY.SYS.DDF01 for a contactless chip. The Candidate List built via PSE is called indirect or implicit Application Selection.
Payment Systems
Agentic Commerce Protocol (ACP) is a next-generation protocol that lets AI agents integrate directly into commercial processes such as payments, orders, refunds and subscriptions. This post explains how it works and what it offers businesses.
Payment Systems
Digitalization keeps changing the speed and shape of payments. AI-based payment agents pay on their own within user-defined limits and rules, completing transactions without the user initiating any action. This post explains how they work and what to watch for.
Online & Authorization
You press the pay button and the screen says the transaction failed. Behind that failure are checks on your balance and transaction security. This post explains how funds confirmation APIs work, where they apply, and the situation in Turkey's open banking.
FAST
Request to Pay lets users request payment from people who owe them money through a banking application. The CBRT has expanded the FAST Request to Pay Overlay Service so that corporate users can also use it.
Payment Systems
Open banking means sharing financial data with third parties securely, and Payment Services Data Sharing Services (OHVPS) are the two core payment services under it. This post explains both and where to find the participant list on the BKM website.
Payment Institutions & E-Money
The CBRT published its Communique on the Redetermination of the Minimum Equity Amounts of Payment and E-Money Institutions in the Official Gazette. The new amounts apply from 30 June 2025.
ATM
Due to inflation and other financial conditions, banks in Türkiye raised their ATM cash withdrawal limits as of 1 January 2025, from 10,000 TL to 15,000 TL and, at some banks, up to 20,000 TL.
Merchant & POS
BKM has changed the domestic transaction flows for contactless transactions above and below the CVM limit. For above-limit transactions, the issuer can now ask the cardholder to re-enter the PIN instead of terminating the transaction after an incorrect PIN (DE39 = 55).
Payment Systems
The domestic authorization flow for below-CVM-limit online contactless transactions has changed. Issuers can now ask the cardholder for a PIN or request card insertion instead of simply approving or declining. This post explains the CVM list and the new DE48 PDS22 and DE39 = 65 message flows.
Merchant & POS
It is not possible to initiate an EMV transaction directly with credit card Track Data (magnetic stripe data), because EMV transactions use a different technology and security mechanism. Why can't an EMV transaction be initiated with Track Data?
Payment Systems
An amendment was made to the communiqué on the information systems of payment and e-money institutions and data sharing services, setting 31/3/2025 as the deadline for other payment service providers' obligations.