Oh, lets see here, this condition normally happens if the background music Feature 86 is active, so the Feature#86 should cure it.....although another condition may exist....that involves Feature*82 which is dial pad mode.
There are 3 choices for dial pad mode: Be sure your dialpad is set to Standard mode. I have a feeling it might be set on predial. Let me know your results!
Dialing Modes
FEATURE * 82
Choose one of the three methods of dialing.
Press FEATURE * 82
Press # to select the mode
Press HOLD to store the mode.
Standard Dial: Select a line, then dial the number. (Standard Dial is always available, even when another dialing mode is selected.)
Automatic Dial: Dial the number without choosing a line button first. Your prime line is automatically selected for the call.
Pre-Dial: Dial the number, then press a line button to place the call. Edit the number by pressing VOLUME BAR before placing the call.