The Apple-CAT II was popular with phone phreakers for its high half-duplex 1200 bit/s speed and its ability to detect various tones. It also had the ability to "generate" tones directly into the phone line. Several specialized applications such as TSPS, The Cats Meow and Phantom Access were used to mimic standard telephone sounds such as standard numeric DTMF dial tones as well as blue box tones, ringing (both American and International), dial tones, call waiting alerts, busy signals, 2600 Hz tones, and other effects such as payphone sounds. Due to these and other features, the Apple-CAT II could be used as a black box, red box, hacking tool, answering machine, war dialer, voice simulator, voice distorter, etc.