Nobody Can Hear Me.

First, reset the settings on the cordless phone(s).  As this was my friend's phone, I do not have it in hand to give exact details of this process.  However, the instructions for this process are in the manual.  If I remember correctly, this is done by pressing menu and scrolling (arrow keys) down the list to the last choice which is reset settings.  Select by pressing menu button and then it will ask if you want to reset.  Select yes then menu. 
Remove cordless phone(s) from charging base.
Unplug corded phone and charging base(s).
Unplug service wire (Bell, AT&T etc.)
Leave unplugged for about 5 minutes.
Plug in corded phone and charging base(s).
Plug in service wire.
Return cordless phone(s) to charging base(s).
The phone then worked fine.  I am not sure how this problem came to be in the first place, but apparently it had something to do with an attempt to use the mute feature during a conversation.
Hope this works for others.