| 1 | Initiate Payment Request | Merchant Backend | Send encrypted payment data to CellPay. |
| 2 | User Login Prompt | CellPay UI | Redirect user to login securely. |
| 3 | User Authentication | CellPay Backend | Validate credentials and initiate session. |
| 4 | Payment Method Selection | CellPay UI | User selects wallet or linked bank. |
| 5 | Payment Method Validation | CellPay Backend | Validate chosen account and balance. |
| 6 | Payment Confirmation | User + Backend | Confirm details and re-enter password. |
| 7 | OTP Verification | CellPay Backend | Required for transactions above NPR 5000. |
| 8 | Final Validation & Redirect | CellPay Backend | Complete transaction and redirect user. |
| 9 | Access Token Retrieval | Merchant Backend | Obtain token for post-payment queries. |
| 10 | Status Inquiry | Merchant Backend | Verify final transaction result. |