Phantom users in the United States must create or link a Kalshi account and complete identity verification checks including government identification before trading.

From the articlePhantom Starts a Staged US Launch of In-Wallet Prediction Markets - UnchainedAlso in Phantom rolls out Kalshi prediction markets to US users, says it's 'confident and comfortable' amid state lawsuits, Phantom Launches Kalshi Prediction Markets for U.S. Users, Phantom brings Kalshi prediction markets to US users as legal fights mount, Phantom brings Kalshi markets to US users with $0.02 contract fees