Asterisk Groups

There are several concepts called "groups" in Asterisk, and it's not always clear which one is being spoken of, or if they are related. This page attempts to enumerate them, with a short description and a link to their actual documentation.

NB: these groups have nothing to do with Asterisk User Groups.

Channel groups

As the name implies, these are used to group channels (that is, ongoing communications). The main operations are:

• making the current channel join a given group (alphanumeric identifier),
• count the amount of channels currently belonging to a given group (exact or pattern match).

Since internally, groups are just channel variables, they are unset when the channel they were set on dies.

The main usage of this feature is to manually enforce limits on channels. For example, to forbid more than two external SIP channels at once if your internet connection cannot do better. Some people also use it to restrict incoming calls on SIP phones to one, and to produce a busy tone when the user is already talking.

A channel may belong to one group per category only. So, if one wants to make a channel belong both to Zap and SIP groups because two such channels are being bridged, one would have to use Zap@in and SIP@out (creating the categories in and out). Of course, to determine how much SIP channels are in use overall, it would then be necessary to sum the group counts of SIP@in and SIP@out.

The means to temper with channel groups in Asterisk 1.0 were the following applications:

• GetGroupCount()
• GetGroupMatchCount()
• SetGroup() - this page includes additional information and examples
• CheckGroup()

These are now deprecated in 1.2 and replaced by the following functions:

• GROUP() (replaces both SetGroup() and CheckGroup())
• GROUP_COUNT()
• GROUP_MATCH_COUNT()
• GROUP_LIST()

Call groups and pickup groups

This kind of group is used to allow picking up remotely a ringing phone through *8(#) (by default, it is denied). The call group is what an extension belongs to, the pickup group is which callgroups the extension can remotely pick up.

This mechanism is unfortunately local to a technology/driver, although patches can lift this limitation.

See Asterisk callgroups and pickupgroups for more information.

Trunk groups

Groupping Zapata FXO ports into trunk groups allow automatic selection of an idle port for outgoing calls.

See zapata.conf for more information.

Agent groups

This feature allows managing agents through groups rather than individually.

See agents.conf and queues.conf for more information.