Our agreement with our network operator HISPs only allows directory data to be shared with the clients/users of other participating member HISPs. Nearly every healthcare organization or practice in the United States is served by a member HISP, and therefore should have access to the DirectTrust directory through their HISP.
The aggregated directory currently contains about half of all DirectTrust addresses. Why? Our agreement with our HISPs allows for privacy: addresses are only published if an organization chooses to share their addresses with the directory as a whole. While there are reasons for not publishing a Direct address, we encourage users to opt in to sharing their addresses.