detecting and saving a called extension number sent by {HEAD ~ said central office} from {TAIL ~ a calling party} on a direct in dial trunk line into said PBX, 
from
detecting and saving a called extension number sent by { HEAD ~ said central office } from { TAIL ~ a calling party } on a direct in dial trunk line into said PBX ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH