Add-on module for a telephone

FIG. 1 is a front perspective view of an add-on module for a telephone showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left-side elevational view thereof;

FIG. 5 is a right-side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is another perspective view thereof, showing our new design in an alternate position in which the stand for the add-on module is unfolded.

The broken lines in the figures depict environmental subject matter and form no part of the claimed design.