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