{HEAD ~ The access controller} 160 includes an interface 710, a DS0 Handler 720, {TAIL ~ a microprocessor unit} 730, a message processor 740, and a clock processor 750 
{ HEAD ~ The access controller } 160 includes an interface 710 , a DS0 Handler 720 , { TAIL ~ a microprocessor unit } 730 , a message processor 740 , and a clock processor 750
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH