AXIS P8221 Network I/O Audio Module provides eight configurable input/output (I/O) ports and audio capabilities to a network video system that either does not have such support or require additional support.Sensors such as a door switch, smoke detector, IR detector or glass break detector—used for triggering an alarm event—can be connected as inputs. Output ports can be connected to control devices or relays, for instance, to open/close doors or turn on/off lights upon alarm.AXIS P8221 supports two-way audio and has a built-in low power amplifier for small speakers so there is no need for an external preamplifier. It also has phantom power for a balanced microphone.