VTech DS6151 DECT 6.0 Cordless 2-Line Phone System with Digital Answering System (Single-Handset System)VTech DS6151 DECT 6. 0 Cordless 2 Line Phone System with Digital Answering System (Single Handset System) DECT 6. 0 technology; Caller ID; Expandable up to 12 handsets; Handset & base speakerphones; Answering machine mailbox for each line; Features intercom & ability to transfer calls; Dual keypad; Single handset system;