API IntegrationIntegration Types
Issuer Host Integration
Integration guide for banks acting as issuer — CBS adapter integration for processing NPCI messages.
| Aspect | Detail |
|---|---|
| Partner Type | Bank acting as issuer (customer's money is at this bank) |
| App Ownership | No customer-facing app required |
| Integration Mode | CBS Adapter (M2P → Bank CBS) — bank exposes CBS APIs |
| M2P Role | UPI Switch (issuer mode) — handle all NPCI messages, translate to CBS calls |
| Partner Role | Expose CBS APIs for debit/credit/balance/account operations |
Unlike all other GTMs where the partner calls M2P, in Issuer Host M2P calls the partner's CBS system.
Integration Direction
| M2P Handles | Partner Provides |
|---|---|
| Receives NPCI ReqPay, ReqRegMob, Mandate messages | CBS adapter APIs (REST/SOAP) |
| Translates NPCI XML to CBS calls | Account debit/credit operations |
| Sends RespPay back to NPCI | Balance inquiry response |
| Handles UPI registration (ReqRegMob) | Mobile-to-account mapping |
| Processes mandates (pre-debit, execution) | Mandate debit execution |
| Manages disputes (UDIR) | Dispute response & evidence |
CBS Adapter — APIs the Bank Must Expose
M2P calls these endpoints as NPCI transactions are received:
| # | CBS Operation | Triggered By | Purpose |
|---|---|---|---|
| 1 | fetchAccountsByMobile | ReqRegMob | Return accounts linked to mobile number |
| 2 | fetchAccountsByAccount | Various | Check if account is active |
| 3 | fundTransfer (Credit) | ReqPay (CREDIT) | Credit customer for incoming payment |
| 4 | fundTransfer (Debit) | ReqPay (DEBIT) | Debit customer for outgoing payment |
| 5 | fundTransfer (Reversal) | Failed transaction | Reverse a debit or credit |
| 6 | fundTransfer (Refund) | Refund request | Process refund to customer |
| 7 | balanceInquiry | ReqBalEnq | Return account balance |
| 8 | lienAdd | Mandate creation | Place hold on account |
| 9 | lienRemove | Mandate revoke/expiry | Remove hold from account |
| 10 | lienExecute | Mandate execution | Execute held amount |
| 11 | cardValidation | PIN set/reset flows | Validate debit card details |
| 12 | transactionEnquiry | Various | Enquiry for all transactions |
| 13 | validateVpa | ReqValAdd | Validate VPA belongs to account |
| 14 | fetchAccountDetails | Various | Fetch account metadata |
| 15 | upiLiteTopUp | UPI Lite | Top up UPI Lite balance |
| 16 | upiLiteDebit | UPI Lite txn | Debit UPI Lite balance |