If a keyboard character is not working after installing Apple Telecom 3.0, below is a description of what may have happened.
While in Apple Phone if you:
1) clicked the Opens Preferences Window button or choose Preferences under
the edit menu,
2) clicked the Modem option,
3) selected the "use the key combination for answering/hanging up any
application",
the default is set to command-space. If you set this to the letter "A" for example, this letter will continue to function in key caps but will stop working in other applications.
Try changing the key character set in "use the key combination for answering/hanging up any application", to a more unique key combination to resolve this.