In step 507, bridging and signaling {HEAD ~ unit} 109 provides answer supervision on {TAIL ~ the callers} telephone call 
In step 507 , bridging and signaling { HEAD ~ unit } 109 provides answer supervision on { TAIL ~ the callers } telephone call
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH