It most certainly can, I added a VTech cs6709, this is how I did it step one go to the cs6114 take the phone off the base and hold the find button for approximately 6 seconds this will put the base into registration mode take the phone that you want to register cs6709 and hold the pound key # it will say registering and it will take approximately 60 seconds and the phone will beep when registered mine said handset #2 registered, so don't believe what they tell you that you cannot expand this phone I don't know what other handsets will work but I imagine any 6.0 phone VTech or AT&t will work I'm not positive on that only the model that I registered I can say for sure it worked thank you.