Indicates the special digits which can appear in dialed digit strings
BIT 0 - Is digit A allowed in the digit string
BIT 1 - Is digit B allowed in the digit string
BIT 2 - Is digit C allowed in the digit string
BIT 3 - Is digit D allowed in the digit string
BIT 4 - Is digit E allowed in the digit string
BIT 5 - Is digit F allowed in the digit string
BIT 6 - No special digits in the digit string