# Ethereum and Bitcoin testnet The SDK addresses it by exposing the `TBTC.initializeSepolia` function. That function: * Takes an Ethers signer or provider as a parameter and uses it to interact with tBTC contracts deployed on Ethereum Sepolia * Automatically configures an Electrum Bitcoin client to communicate with the Bitcoin testnet (communication is done through a set of pre-configured Electrum servers) The usage of this function is exactly the same as for the previous `TBTC.initializeMainnet` function. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.threshold.network/app-development/tbtc-sdk/guides/initialize-sdk/ethereum-and-bitcoin-testnet.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.