# offline The Offline transport is a dummy implementation to signal that there is no comms server available in a realm. It's commonly used in testing and development environments. The transport never emits incoming messages, and ignores all outgoing messages. If you want an offline variant with simulated behavior, see [Simulator](/docs/contributor/communications/transport-types/simulator/) instead. URIs have this look: ``` offline: ``` What comes after the `offline:` prefix is unspeficied, and can be used by implementations (or left empty) as they see fit.