Used in applications where calling access is essential but the installation of a phone may be impractical. The AVAYA Door Phone is designed to connect a telephone extension to the system so as visitors can call a pre-programmed extension by pressing the call button on the remote stainless steel speaker panel. Features include: high quality, vandal & weather resistant stainless steel housing, auto answer option, telephone powered line, 30 second call time out limits and an adjustable microphone and speaker volume, all in a weather and temper resistant case. Adjustable call timer duration (15 sec. to 2 minutes) Controller.