Inter-call device for telephone sets
FIG. 1 is a front elevational view of a inter-call device for telephone sets showing my new design; 
     FIG. 2 is a rear elevational view thereof; 
     FIG. 3 is a top plan view thereof; 
     FIG. 4 is a bottom plan view thereof; 
     FIG. 5 is a left side elevational view thereof; 
     FIG. 6 is a right side elevational view thereof; 
     FIG. 7 is a perspective view thereof; 
     The broken line showing of vertical lines on the keyboard in FIGS. 1 and 7 is for illustrative purposes only and forms no part of the claimed design.