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