Baseline: crypto over a phone call
We built a voice assistant that gives anyone a wallet by dialing a phone number, and won the grand prize at the ETHDenver 2025 hackathon.
The pitch was simple: anyone should be able to buy crypto by making a phone call. No app, no wallet setup, no seed phrase. You dial a number, you talk, and it works.
That became Baseline, our team's entry for the ETHDenver 2025 #BUIDLathon. It won the Infrastructure + Scalability track ($7,000 plus 12K $SPORK, awarded through quadratic voting by 50 community judges), along with Coinbase bounties for Most Innovative Use of AgentKit and Best Use of CDP SDK.
Problem Statement
How it worked
Calling the number instantly provisioned an embedded wallet. From there, everything ran on voice:
- A phone and voice interface fed into an OpenAI-powered orchestration layer that controlled a swarm of specialized AI agents
- Agents executed on-chain actions through Coinbase Developer Platform AgentKit: buying USDC, staking, deploying contracts, and purchasing NFTs
- Privy handled authentication with Coinbase Smart Wallets, Coinbase Onramp covered fiat deposits, and ORA provided decentralized inference, all running on Base
- A dashboard tracked the portfolio in real time for users who did want a screen
What I took from it
Voice is an unforgiving interface for financial actions. There is no confirmation modal, so the orchestration layer has to be defensive: repeat amounts back, confirm every transfer explicitly, and fail closed. Designing agents around that constraint taught me a great deal about safe AI tool-calling.
Tech Stack
Built in one weekend with Jochen and Scott, and judged by a panel of 50 community judges.