The VTech Accessory Handset (IS7101) lets you expand your phone system with a second handset. It can be placed in a different area of the house for convenience. This VTech handset is an easy way to get more functionality out of your VTech IS7121-2 phone system. This phone includes mute, caller ID and last number redial functions. The handset requires the IS7121-2 base to operate.