Appendix A. Dial Plans

The SIP code will allow provisioning (via web browser) of the dial plan. A dial plan gives the unit a map to determine when a complete number has been entered and should be passed to the gatekeeper for resolution into an IP address. Dial plans are expressed using the same syntax as used by MGCP NCS specification.

The formal syntax of the dial plan is described in the following notation: Digit ::= "0" "1" "2" "3" "4" "5" "6" "7" "8" "9"

Timer ::= "T" "t"

Letter ::= Digit Timer "#" "*" "A" "a" "B" "b" "C" "c" "D" "d" Range ::= "X" "x" -- matches any digit

"[" Letters "]" -- matches any of the specified letters Letters::= Subrange Subrange Letters Subrange::= Letter -- matches the specified letter

Digit "-" Digit -- matches any digit between first and last Position::= Letter Range

StringElement::= Position -- matches any occurrence of the position Position "." -- matches an arbitrary number of occurrences including 0

String ::= StringElement StringElement String StringList::= String String "" StringList DialPlan::= String "(" StringList ")"

A dial plan, according to this syntax, is defined either by a (case insensitive) string or by a list of strings. Regardless of the above syntax, a timer is only allowed if it appears in the last position in a string (12T3 is not valid). Each string is an alternate numbering scheme. The unit will process the dial plan by comparing the current dial string against the dial plan. If the result is under-qualified (partial matches at least one entry), then it will do nothing further. If the result matches or is over-qualified (no further digits could possibly produce a match), then it sends the string to the gatekeeper and clear the dial string. The Timer T is activated when it has all that is required to produce a match. The period of timer T is 4 seconds. For example, a dial plan of (xxxTxxxxx) will match immediately if 5 digits are entered. It will also match after a 4 second pause when 3 digits are entered.