Telephone instrument base
FIG. 1 is a left side, top and front perspective view of a telephone instrument base, showing my new design; 
     FIG. 2 is a top plan view thereof; 
     FIGS. 3 and 4 are respectively front and rear elevational views thereof. 
     FIG. 5 is a left side elevational view thereof; and 
     FIG. 6 is a right side elevational view thereof. 
     The broken line showing of the handset in FIG. 1 is for illustrative purposes only and forms no part of the claimed design.