An apparatus and method for an alert and signal management device for an already engaged telephone line is described. The device can interface to either a modem of FAX or answering machine, and to a telephone and is triggered by conventional call waiting or distinctive call waiting SAS tones. It will alert by audible and visual means. When a subscriber answers the third party's call a switching circuit is activated that disconnects any local modem or FAX interfaced to the device and signals a switch-hook flash. This allows a call waiting party to commence in conversation or a data-signal to be received. The device also incorporates a switch to select automatic answer mode to allow a subscriber to share an engaged telephone line with in-coming calls to a FAX machine. Upon completion of these in-coming calls the device will automatically switch back to the previously engaged telephonic device.