Communication apparatus, phone set, communication system, communication method

In the present invention, there is provided a communication apparatus including: a first communication section for a communication through a first communication path; a second communication section for a communication through a second communication path; a communication-path determination section to determine whether a present communication path currently being used is the same as a specified communication path specified as a communication path to be used, where the present communication path and the specified communication path are one of the first and second communication path, respectively; and a communication-path switching section to replace one of the first and second communication sections with the other communication section in order to replace the present communication path with the specified communication path in the course of a communication if the determination result produced by the communication-path determination section indicates that the present communication path is not the same as the specified communication path.