The service authentication code is communicated to the user via {HEAD ~ the communications network} and received, or entered, into {TAIL ~ an authentication device} associated with the user  
The service authentication code is communicated to the user via { HEAD ~ the communications network } and received , or entered , into { TAIL ~ an authentication device } associated with the user
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH