By inserting the access code into the dialed number the device selects {HEAD ~ a particular long distance carrier} for {TAIL ~ the duration} of the call 
for
By inserting the access code into the dialed number the device selects { HEAD ~ a particular long distance carrier } for { TAIL ~ the duration } of the call
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH