These jacks are available at many hardware and electronics stores, or can be installed by the local phone company. A REN is used by the telephone company to determine the maximum number of devices that may be connected to a telephone line and still ring when that telephone number is dialed. In most areas, the REN should not exceed five. Short burst phones may not provide a long enough tone to access the remote features on many answering machines. Tone Dialing or Touchtone is most commonly associated with a push-button telephone.
Tones signal the telephone company switching equipment indicating the number dialed.
True Touchtone A true touchtone phone is one that emits a continuous tone as long as a button is pressed on the keypad. Remote Operation may require the use of a true touchtone phone. All Casio Communications answering machines use a VOX circuit to disconnect the phone after a caller is through leaving a message. The VOX circuit either recognizes no sound or a continuous sound such as a dial tone of three to five seconds and disconnects the phone call. Sometimes on a very noisy phone line, it may take the unit longer to disconnect.