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  2. Sound-powered telephone - Wikipedia

    en.wikipedia.org/wiki/Sound-powered_telephone

    A dial telephone system with a battery backup will not meet the USCG Regulations as they currently exist. Other uses for sound-powered telephone technology today include emergency communications systems for high-rise buildings, draw bridges, ski lifts, and temporary locations where reliable communication is necessary.

  3. Backup battery - Wikipedia

    en.wikipedia.org/wiki/Backup_battery

    Additionally these batteries power the remote cellular phone systems that thwart phone line snipping as well. The backup battery usually has a lifespan of 3-10 years depending on the make and model, and so if the battery runs flat, there is only one main source of power to the whole system which is the mains power.

  4. Battery room - Wikipedia

    en.wikipedia.org/wiki/Battery_room

    Telephone system central offices contain large battery systems to provide power for customer telephones, telephone switches, and related apparatus. [2] Terrestrial microwave links, cellular telephone sites, fibre optic apparatus and satellite communications facilities also have standby battery systems, which may be large enough to occupy a separate room in the building.

  5. Emergency power system - Wikipedia

    en.wikipedia.org/wiki/Emergency_power_system

    A backup generator for a large apartment building A backup power fuel cell for telecom applications A portable emergency power generator in a shipping container. An emergency power system is an independent source of electrical power that supports important electrical systems on loss of normal power supply.

  6. Field telephone - Wikipedia

    en.wikipedia.org/wiki/Field_telephone

    The first field telephones had a battery to power the voice transmission, a hand-cranked generator to signal another field telephone or a manually-operated telephone exchange, and an electromagnetic ringer which sounded when current from a remote generator arrived. This technology was used from the 1910s to the 1980s.

  7. Uninterruptible power supply - Wikipedia

    en.wikipedia.org/wiki/Uninterruptible_power_supply

    A large data-center-scale UPS being installed by electricians. An uninterruptible power supply (UPS) or uninterruptible power source is a type of continual power system that provides automated backup electric power to a load when the input power source or mains power fails.