Appendix C. Functions in the dialplan
In addition to dialplan applications, which have been part of
Asterisk almost from the very beginning, Asterisk also supports functions
as of Asterisk 1.2. This is part of a long-standing effort to make
Asterisk behave more like a programming environment. In contrast to
applications, functions may not be called directly. Instead, they are
called inside applications and return a value, or -- in a departure from
the classical definition of a function -- they may even be written to
using the application
Set() (see
Section B.110, “Set()”). Function names are always written in
uppercase letters. Surprisingly, functions are written in the same way as
variables, inside curly braces and preceded by a $ character (
${} ). This is necessary because strings are not always
bounded by quotation marks.
To find out which functions are currently available in your
installation, enter show functions and
show function
FUNCTIONNAME or core
show functions and core show function
FUNCTIONNAME (depending on your
Asterisk version) in the CLI.[]Note that these commands are case-sensitive. Function names
must be written entirely in uppercase.