NOVELTY - The supply (100) has a power supply module (110) converting an alternating current (AC) signal into a direct current (DC) signal. The module provides the converted DC signal to a power over Ethernet (POE) port (140) and monitors an AC input interface to identify an interruption in the AC signal. The module tests a chargeable battery based secondary power supply i.e. lithium-ion polymer battery cell, to ensure whether the power supply is operated correctly. The module switches power provided to the port from the converted DC signal to the secondary power supply.    USE - Multi-functional power supply for providing power to a load of a power supply system (claimed) in a distributed wireless networking environment i.e. router/switch type environment. Uses include but are not limited to a wireless router, Ethernet hub, switch, private branch exchange (PBX) system, wireless access point (AP) and an internet protocol (IP) phone.    ADVANTAGE - The supply can effectively provide power over Ethernet (POE) functionality and uninterrupted power supply (UPS) requirements to power mounted devices, thus easily reducing the significant costs in the network deployment. The supply enables the powered devices to be located in strategic locations without being limited by the provision of alternating current (AC) power outlets. The supply allows the Ethernet switch vendors to implement POE within each switch port, thus avoiding the need for separate power hubs, and enables plugging of the data cable from POE-enabled access points directly into the Ethernet switch in an effective manner. The supply can easily ascertain the load required on the battery by monitoring the load on the current power supply in an effective manner.    DESCRIPTION OF DRAWING(S) - The drawing shows a functional block diagram of components of a multi-functional power supply.    Multi-functional power supply (100)    Power supply module (110)    Auto transfer switch (114)    Charger (116)    Power over Ethernet port (140)