[SIP] Digit Maps Syntax Definition

[SIP] Digit Maps Syntax Definition



The formal syntax of the digit map is described by the following BNF notation:

Digit          ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

Timer          ::= "T" | "t" -- matches the detection of a timer

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 , (".") which matches an arbitrary number

StringElement   ::= Position           -- matches an occurrence of the position

| Position "."       -- matches an arbitrary number of occurrences

-- of the position, including 0

String         ::= StringElement | StringElement String

StringList      ::= String | String "|" StringList

DigitMap       ::= String | "(" StringList ")"

DTMF     A digit, a timer, or one of the symbols "A", "B", "C", "D", "#", or "*".  Extensions may be defined.

Wildcard: The symbol "x" which matches any digit ("0" to "9").



Reference :

Digit Maps used to Define the Dial Plan