How do I turn off the key pad tone on the impression sgh-a877

The Sound Profile only covers call sounds.
Sound Profiles
This menu allows you to specify how you are informed of
incoming calls.
Selecting a Profile
1. Touch ➔ Settings ➔ Sound Profile.
2. Touch the radio button next to the profile name. The
selected profile activates. Choices include:
• Normal
• Silent
• Driving
• Outdoor
Normal Profile
The phone’s profile defaults to Normal. Use the following
procedures to change the profile.
Editing the Normal - Call Profile
1. Touch ➔ Settings ➔ Sound Profile ➔ Normal.
• Touch the name field and not the radio button to the right.
2. Touch drop-down menu (upper-right of the screen) and
select Call.
3. Select the Call Alert Type field and select one of the
following and touch Save:
• Melody: the phone rings using the ring melody selected in the Ring
tone menu.
• Vibration then Melody: the phone vibrates and then starts ringing.
• Vibration & Melody: the phone vibrates and plays a melody
simultaneously.
4. Touch the Voice Call Ringtone field, touch to select a
ringtone and touch Save.
5. Drag the Ringtone Volume slider to the volume level you
desire (range is 1-7).
6. Touch the Vibration Pattern field, then touch to select
Vibration 1 - 5.
7. Touch Save to return to the Sound Profiles menu.
There is no mention of keyboard tones in the user manual.

Go to phone settings then check with keypad tone options