telephony over lan system having a graphical user interface wherein an authorized or guest user may be locked within a tol window having full access to the tol features but denied access to other parts of the computer system in such a system the terminal user or subscriber may click on a u201c guest u201d button on the tol client gui screen before leaving the computer the tol guest user may then execute the call normally according to a first embodiment of the invention the tol client locks the user into the tol client screen keystrokes and mouse cursor movements which would allow exiting the tol client are prevented according to a second embodiment of the invention the tol client screen is u201c maximized u201d and the minimize or resize window functions are blocked when the terminal subscriber returns a password is entered to regain full access to the computer application_number US 33380699 A description turning now to the drawings and with particular attention to fig1 an exemplary computer 10 including a system unit 11 a keyboard 12 a mouse 13 and a display 14 are depicted the computer 10 may include tol client terminal functionality according to the present invention the screen 160 of the display device 14 is used to present the graphical user interface gui and particularly the tol client window 3008 the graphical user interface supported by the operating system allows the user to employ a point and click method of input i e by moving the mouse pointer.