Patent ID: 8526585

Claim:
A communication terminal device capable of being connected with an external telephone and of receiving and transmitting facsimile data from and to a network, comprising: an off-hook detector configured to detect an off-hook condition of the external telephone, a semiconductor DAA (Digital Access Arrangement) including an impedance switcher configured to switch impedances and a direct-current resistance switcher configured to switch direct-current resistances; an impedance switching controller configured to instruct the impedance switcher to switch the impedances; a direct-current resistance switching controller configured to instruct the direct-current resistance switcher to switch the direct-current resistances, wherein, when the off-hook detector detects the off-hook condition of the external telephone, the impedance switching controller instructs the impedance switcher to switch the impedances and the direct-current resistance switching controller instructs the direct-current resistance switcher to switch the direct-current resistances, wherein the off-hook detector comprises one of a photo-coupler to detect the off-hook condition of the external telephone, or a current detecting element to detect the off-hook condition of the external telephone.