For the sake and sanity of the user of this software, we need to cover the basic elements of the configuration before getting to the meat and potatoes.

1. Configuration Directives
2. Comments
3. Other

There are five (5) types of configuration directives used with Kamailio.

1. C-Style Control Directives
2. Apache Name/Value Pairs
3. Normal Name/Value Pairs
4. Modify Parameter Procedure
5. Route Functions

Configuration file comments are PHP style, without the double-slash line comment. Only hash (#) will work for line comments.
This gets confusing since the hash-bang (#!) is used at the beginning of the C-Style Control Directives.

/* block comment
   block comment */
// this is NOT a line comment
# this is a line comment
#!c_style_directive

The semicolon works with all forms of configuration directives as an instruction separator. Allowing for comments or additional configuration directives on the same line.

configuration_directive_a; configuration_directive_b
configuration_directive; # comment about the configuration directive

Available directives:

• #!define NAME - define a keyword
• #!define NAME VALUE - define a keyword with value
• #!ifdef NAME - check if a keyword is defined
• #!ifndef - check if a keyword is not defined
• #!else - swtich to false branch of ifdef/ifndef region
• #!endif - end ifdef/ifndef region
• #!trydef - add a define if not already defined
• #!redefine - force redefinition even if already defined
• #!subst
• #!substdef

#!define MODULE_NAME

#!ifdef MODULE_NAME
 .. set directives ..
#!else
 .. set alternate directives .. 
#!endif

name "value"

The value MUST be enclosed in quotes.

loadmodule "module_name.so"
loadmodule "another_module.so"
include_file "file_to_include.cfg"
import_file "/path/to/file_to_import.cfg"

name=value

(delimited by an equals sign)

core_parameters

memdbg=5
memlog=5
log_facility=LOG_LOCAL0
fork=yes
children=4
#disable_tcp=yes
auto_aliases=no
alias="sip.mydomain.com"

modparam("first_module", "module_parameter_text", "new_value");  # Set Text Value
modparam("second_module", "module_parameter_number", 10000);      # Set Numeric Value
modparam("second_module", "module_parameter_on", 1);              # Enable Parameter
modparam("third_module", "module_parameter_on", 0);             # Disable Parameter