After making three unsuccessful attempts to pay his telephone bill at the Xian City Commercial Bank, Mr. Yang finally paid the bill only to be shocked by the receipt issued by the bank clerk: after he had just paid off the telephone bill, the receipt still showed an outstanding balance which Mr. Yang could never pay off - a sky-high telephone bill of RMB 4,503,601,774,848.05 owed to the telecom company. Mr. Yang was jokingly called by his friends "the toughest debtor in history".