> ## Documentation Index
> Fetch the complete documentation index at: https://pay-docs.holdstation.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Offramp Flow

> How to sell USDT for VND using Holdstation Pay.

## Overview

The offramp flow allows users to **sell USDT and receive VND**. The partner creates a withdrawal order, shows the recipient address to the user, and the user transfers USDT on-chain. Holdstation Pay then sends VND to the user's bank account.

## Sequence Diagram

```mermaid theme={null}
sequenceDiagram
    actor U as User
    participant P as Partner
    participant H as Holdstation Pay
    participant B as Blockchain
    participant Bank

    U->>P: Request to sell USDT
    Note over U, P: Input amount in USD
    P->>+H: POST /partners/orders/withdrawal
    Note over P, H: Use callback for order state update
    H-->>H: Calculate VND amount to receive
    H-->>H: Lock recipient wallet for this order
    H->>B: Subscribe for Transfer event
    H-->>P: Returns {order + recipient addr}
    P-->>U: Show recipient addr + USDT amount
    U->>B: Transfer exact USDT amount to recipient
    B-->>H: Transfer event log
    H-->>H: Verify transferred amount
    H->>-Bank: Make a VND transfer request
    Bank-->>U: Transfer VND
```

## Processing States Flow

```mermaid theme={null}
stateDiagram-v2
    state "State -> Completed" as C
    state "State -> Failed" as F
    state "State -> Closed" as CL
    state "Crypto Pending = 20" as CP
    state "Crypto Confirmed = 21" as CC
    state "Crypto Failed = 22" as CF
    state "Fiat Pending = 23" as FP
    state "Fiat Confirmed = 24" as FC
    state "Fiat Failed = 25" as FF

    [*] --> CP
    CP --> CC: Transfer event verified
    CP --> CF: Transfer failed
    CP --> CL: Order expired or closed manually
    CF --> F
    CC --> FP: Transfer VND
    FP --> FC: Transfer successful
    FC --> C
    FP --> FF: Failed to transfer
    FF --> F
    F --> [*]
    C --> [*]
    CL --> [*]
```

## Step-by-Step

<Steps>
  <Step title="Create a withdrawal order">
    Call `POST /partners/orders/withdrawal` with the amount, currency, payment info (bank details), token address, chain ID, and callback URL.
  </Step>

  <Step title="Present recipient address">
    Display the `recipient` wallet address and exact USDT amount from the response to the user.
  </Step>

  <Step title="User transfers USDT">
    The user sends the exact USDT amount to the recipient address on the specified blockchain.
  </Step>

  <Step title="Holdstation verifies transfer">
    Holdstation Pay detects and verifies the on-chain transfer event.
  </Step>

  <Step title="VND sent to bank">
    Once verified, Holdstation Pay initiates the VND bank transfer to the user's account. The order moves to **Completed**.
  </Step>
</Steps>