00287nam a22001217a 4500020001600000040000900016082001600025100002000041245002300061250001800084260004100102650002200143  a98141266357  cNUST  a621.385 BEL  aBellamy, C John  aDigital Telephony:  aThird Edition  aNew York:bJohn Willy & Sons,c2003.  aDigital Telephony