The controller inserts {HEAD ~ a five digit prefix}, namely the access code into {TAIL ~ the dialed number} 
The controller inserts { HEAD ~ a five digit prefix } , namely the access code into { TAIL ~ the dialed number }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL