Abstract: The present invention relates to a security codeless telephone unit using bluetooth and communication method using the same. According to the present invention, a communication of a body of a codeless telephone in a portable device of a security codeless telephone with a portable device in a counterpart codeless telephone via a network is safely secured from a wiretapping. In order to accomplish this, the security codeless telephone unit according to the present invention includes the codeless telephone body and a portable device both of which are connected via bluetooth for allowing voice or data communication mode. Thus, if there is a request for switching a security mode from the portable device or the body, the portable device converts voice signals into encrypted digital signals using a voice codec, a vocoder and an encryption module.