BitChat can send messages over Bluetooth, and it uses a mesh network to relay messages across nearby devices. This allows messages to hop from one phone to another, extending coverage beyond the normal Bluetooth range, though the number of hops is limited and depends on nearby devices. When a device in the mesh has an internet connection, certain messages can be published to Nostr, allowing them to move from the local mesh to the global network. Not all messages are automatically sent online, and purely mesh-local chats remain local. Messages sent via Nostr can also be accessed through clients like NYM (Nostr Ynstant Messenger). BitChat combines offline mesh networking with a decentralized protocol to enable both local and global communication.