I hear a beeping sound.

A beeping sound usually indicates one of the following:

• Your battery may be low. Check the battery-charge indicator.
• If you have Call Waiting, someone may be trying to reach you. Press the green key (above the 1) to answer the second call. See Call Waiting for more details.
• One of the phone keys may have been pressed accidentally.
• You may have a voice or text message in your mailbox.
• Your alarm clock feature could be activated.