AT&T SB67138 SB67138 DECT 6.0 Phone/Answering System, 4 Line, 1 Corded/1 Cordless Handset Sold as 1 EA. Four-line SynJTM system base is expandable up to ten handsets or desksets. Mailbox and auto-attendant voicemail on each line. Large backlit display. Features three-way calling, speed dial, redial, mute, hold, selectable ring tones and remote access.