  We present a scheme for secure deterministic quantum communication without
using entanglement, in a Plug-and-Play fashion. The protocol is completely
deterministic, both in the encoding procedure and in the control one, thus
doubling the communication rate with respect to other setups; moreover,
deterministic nature of transmission, apart from rendering unnecessary bases
revelation on the public channel, allows the realization of protocols like
`direct communication' and `quantum dialogue'. The encoding exploits the phase
degree of freedom of a photon, thus paving the way to an optical fiber
implementation, feasible with present day technology.
