FIG. 1 is a top, front left, and front perspective view of a telephone dialing key cover showing my new design;

FIGS. 2 and 3 are respectively right and left side elevational views thereof;

FIGS. 4 and 5 are respectively top and bottom plan views thereof; and

FIGS. 6 and 7 are respectively front and rear elevational views thereof.

The broken line showing of a handset, and base and electric cord in FIG. 1 is for illustrative purposes only and forms no part of the claimed design.