Complex sentence: In terminology devised by phone phreaks, a magenta box is a device used to simulate an incoming call by applying the AC ringing signal voltage to a POTS line to make the telephones on that line ring.
Split into simpler sentences: In terminology devised by phone phreaks, a ringing generator is a magenta box. The device can be used to simulate an incoming call by applying the AC ringing signal voltage to a POTS line to make the telephones on that line ring.