| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephone communication deice capable of easily expanding functions while reducing the manufacturing cost.SOLUTION: A master unit includes relatively inexpensive first interface sections 13 and 14 only within a main body 1, and a relatively expensive expansion interface section 22 is provided to a built-in expansion unit 2A. As a result, compared to a case where inexpensive and expensive two different kinds of interfaces are provided to the main body 1, the manufacturing cost can be reduced. An expansion unit (for example, external expansion unit 2B) connectable to the first interface section 14 can be added without using any built-in expansion unit 2A. Also, expansion is possible by connecting the expansion interface section 22 of the external expansion unit 2B to the expansion interface section 22 of the built-in expansion unit 2A stored in a housing 18 of the main body 1. Therefore, the function can be easily expanded with a single interface provided to the main body 1. |
