Cisco 8811:
Turn on from Navigation Ring:
You can enable or disable the Voice Feedback feature by pushing the Select button on the Navigation ring three times.
Turn on from Setting Menu:
Step 1: Press Applications 
.
Step 2: Select .
Step 3: Select On to enable the feature.
Step 4: Select Exit twice to save your settings and return to Applications.
Turn off from the Setting Menu:
If you would like to turn off the voice feedback option on your phone:
Step 1: Press Applications .
Step 2: Select .
Step 3: Select Off to disable the feature.
Step 4: Select Exit twice to save your settings and return to Applications.
Please refer to the Cisco IP Phone 8800 Series User Guide for a complete list of phone features.