Hi - The VTech CS5119-2 is an expandable phone system. You can add or replace faulty handsets. The telephone base can have up to 5 cordless handsets. The cordless handset compatible with the base is the model VTech CS5109. For mode details, please contact our Consumer Sales and Service Center between the hours of 9:00 AM and 5:00 PM Monday through Friday at 1-800-595-9511.