The natural question, of course, is which state’s jurisdiction applies. If the caller is in New York, for example, which has a one-party consent law, but the person being called is in Washington, which requires all-party consent, there isn’t necessarily a clear default. Andy Sellars, a staff attorney and fellow at the Harvard Law School Cyberlaw Clinic, told The Verge that the case’s users should probably err on the more conservative side. Getting consent from all parties is always a safe bet.

Source: This iPhone case can record all your calls | The Verge