 This system would fail if any provision was made to allow the subscriber to turn off the bells (do not disturb) for privacy or unplug the telephone; it also presumed that each subscriber only had one telephone connected to the line.One variation of identifying the calling party on direct-dialed long-distance calls is a party code, usually a single digit inside a circle displayed on the phone's number tag.The dialing sequence for such calls is "1" (access number for DDD), the party code, the area code, and the desired number (1 + party code + area code + number).