This object specifies the period between receiving
digits. The timer is not started until the first digit
is received.
The GW starts this timer during digit collection when
at least one or more digits is required for a digit
string to match any allowed pattern in the digit map.
The timer is restarted after every new digit is
received. This continues until the digit string matches
at least one pattern in the digit map.
The value of 0 indicates the timer will not be started
and GW would wait forever.