Panasonic KX-TGA950B Accessory 2 Line Handset for KX-TG954X-Series (3 Handset) w/ Aristic 25 Foot Coiled Handset Cord You can use 3-LINE, 2-LINE with Link-to-Cell. The 2-line Answering System Settings Power Back-Up Operation Stop Unwanted Calls, Call Block Easy to use design