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

# Quickstart: Subscribe and redeem USYC using the Teller smart contract

The Teller contract is an audited smart contract that handles USYC subscriptions
and redemptions. It is implemented with Solidity and you can interact with it
using Solidity, TypeScript, or any other programming language that supports
Ethereum smart contracts.

<Note>
  This quickstart uses testnet addresses. For mainnet addresses, see [USYC
  Contract Addresses](/tokenized/usyc/smart-contracts).
</Note>

The following example shows you how to call the Teller contract to subscribe to
and redeem USYC:

<CodeGroup>
  ```solidity Solidity theme={null}
  import "../IERC20.sol";

  interface ITeller {
    function deposit(uint256 _assets, address _receiver) external returns (uint256);
    function redeem(uint256 _shares, address _receiver, address _account) external returns (uint256);
  }

  ITeller teller = ITeller(0x96424C885951ceb4B79fecb934eD857999e6f82B);

  // Subscribe to USYC
  IERC20 usdc = IERC20(0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238);
  uint256 usdcAmount = 100 * 1e6; // 100.000000 USDC
  address usycReceiver = address(this); // Address to receive USYC
  usdc.approve(address(teller), usdcAmount);
  uint256 usycPurchased = teller.deposit(usdcAmount, usycReceiver);

  // Redeem USYC
  IERC20 usyc = IERC20(0x38D3A3f8717F4DB1CcB4Ad7D8C755919440848A3);
  uint256 usycAmount = 100 * 1e6; // 100.000000 USYC
  address usdcReceiver = address(this); // Address to receive USDC
  address usycAccount = address(this); // Address that holds USYC
  uint256 usdcPayout = teller.redeem(usycAmount, usdcReceiver, usycAccount);
  ```

  ```typescript TypeScript theme={null}
  import { Address, erc20ABI, writeContract, getAccount } from "@wagmi/core";

  const USYC_TELLER_ABI = [
    {
      inputs: [
        { internalType: "uint256", name: "_assets", type: "uint256" },
        { internalType: "address", name: "_receiver", type: "address" },
      ],
      name: "deposit",
      outputs: [{ internalType: "uint256", name: "", type: "uint256" }],
      stateMutability: "nonpayable",
      type: "function",
    },
    {
      inputs: [
        { internalType: "uint256", name: "_amount", type: "uint256" },
        { internalType: "address", name: "_receiver", type: "address" },
        { internalType: "address", name: "_account", type: "address" },
      ],
      name: "redeem",
      outputs: [{ internalType: "uint256", name: "", type: "uint256" }],
      stateMutability: "nonpayable",
      type: "function",
    },
  ] as const;

  // Ethereum Sepolia Addresses
  const SEPOLIA_CHAIN_ID = 11155111;
  const USYC_TELLER_ADDRESS: Address =
    "0x96424C885951ceb4B79fecb934eD857999e6f82B";
  const USDC_ADDRESS: Address = "0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238";
  const USYC_ADDRESS: Address = "0x38D3A3f8717F4DB1CcB4Ad7D8C755919440848A3";

  const ONE_HUNDRED_USDC = BigInt(100_000000); // USDC uses 6 decimals
  const ONE_HUNDRED_USYC = BigInt(100_000000); // USYC uses 6 decimals

  // Subscribe to USYC
  export const approveUSYCTellerToSpendUSDC = () =>
    writeContract({
      chainId: SEPOLIA_CHAIN_ID,
      address: USDC_ADDRESS,
      abi: erc20ABI,
      functionName: "approve",
      args: [USYC_TELLER_ADDRESS, ONE_HUNDRED_USDC],
    });

  const usycReceiverAddress: Address = getAccount(); // Address to receive USYC

  export const depositUSYC = () =>
    writeContract({
      chainId: SEPOLIA_CHAIN_ID,
      address: USYC_TELLER_ADDRESS,
      abi: USYC_TELLER_ABI,
      functionName: "deposit",
      args: [ONE_HUNDRED_USDC, usycReceiverAddress],
    });

  // Redeem USYC
  const usdcReceiverAddress: Address = getAccount(); // Address to receive USDC
  const usycAccountAddress: Address = getAccount(); // Address that holds USYC

  export const redeemUSYC = () =>
    writeContract({
      chainId: SEPOLIA_CHAIN_ID,
      address: USYC_TELLER_ADDRESS,
      abi: USYC_TELLER_ABI,
      functionName: "redeem",
      args: [ONE_HUNDRED_USYC, usdcReceiverAddress, usycAccountAddress],
    });
  ```
</CodeGroup>