To directly make a telephone call to an extension telephone set of the other party destination by providing an extension telephone exchange with an automatic dialing means, receiving a telephone call that is received from the outside once and connecting the call that is externally received to an extension telephone set according to the number of an extension telephone which is sent as speech communication content.

An extension telephone exchange 12 once receives a telephone call when there is the call from an external telephone set 11 and decides whether or not the number of an extension telephone is included in speech communication information. As a result of it, when the number of an extension telephone is included, it records the number and next decides whether or not an extension telephone set 13 that corresponds to the number exists and automatically dials to the set 13 when it exists. With this, it is possible to automatically connects to a prescribed extension telephone set 13 through the exchange 12 if a telephone number and an extension telephone number are continuously dialed from the set 11.