These are OEs (``office equipment''), jumped onto the grey tie frame, which is hard-wired onto the toll frame. I believe that each OE provides one dial-tone phone line, and that the the tie frames are connected to the D4 channel bank. (Forgive my fuzzy understanding; the CO is an mind-bogglingly complex machine.)

Last update: Sun Jan 10 14:01:36 EST 1999, by mark@vielle