System information

Inheriting Channel Variables

Channel variables are always associated with the original channel that set them, and

are no longer available once the channel is transferred.

In order to allow channel variables to follow the channel as it is transferred among the

system, channel variable inheritance must be employed. There are two modifiers that

can allow the channel variable to follow the channel: single underscore and double

underscore.

The single underscore (_) causes the channel variable to be inherited by the channel for

a single transfer, and is no longer available for additional transfers. If you use a double

underscore (__), the channel variable will be inherited throughout the life of that

channel.

Setting channel variables for inheritance simply requires you to prefix the channel name

with a single or double underscore. The channel variables are then referenced exactly

the same as they would be normally (e.g., do not attempt to read the values of channel

variables with the underscores in the variable name).

Here’s an example of setting a channel variable for single transfer inheritance:

exten => example,1,Set(_MyVariable=thisValue)

Here’s an example of setting a channel variable for infinite transfer inheritance:

exten => example,1,Set(__MyVariable=thisValue)

To read the value of the channel variable, do not use underscore(s):

exten => example,1,Verbose(1,Value of MyVariable is: ${MyVariable})

Application Map Grouping

If you have a lot of features that you need to activate for a particular context or exten-

sion, you can group several features together in an application map grouping, so that

one assignment of the DYNAMIC_FEATURES variable will assign all of the designated fea-

tures of that map.

The application map groupings are added at the end of the features.conf file. Each

grouping is given a name, and then the relevant features are listed.

[shifteight]

unpauseMonitor => *1 ; custom key mapping

pauseMonitor => *2 ; custom key mapping

agi_test => ; no custom key mapping

features.conf | 227