sentences:  Once the terminating sender received and stored the digits of the called telephone number, it activated a "terminating" marker, which then used a Number Group Circuit to find the line, marked an idle path, and operated the crossbar switches to use the links to connect the incoming trunk to the line.The Revertive Pulse system as used in 1XB had a "High Five" feature by which the Incoming Brush parameter could be incremented by five.Thus, the new IB numbers 6 through 10 designated a second ten thousand telephone numbers, known as a "B" office.