Yep, the silkscreen has W3 and W4 backwards.
A note to builders:
W3 0 ohm, For National Modem 74HC942
W4 0 ohm, For Texas Inst Modem TMS99532
U35 layout is a direct placement for the 74HC942, the TMS99532 Has To Be Used On A Daughter board...
U35 pin 12 VBB should go to -5V, not +12 as in Jerzy's schematic.