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Building Queues

Written by: Leif Madsen
Initial version: 2010-01-14


Note that this documentation is based on Asterisk 1.6.2, and this is just one approach to creating queues and the dialplan logic. You may create a better way, and in that case, I would encourage you to submit it to the Asterisk issue tracker at for inclusion in Asterisk.

In this article, we'll look at setting up a pair of queues in Asterisk called 'sales' and 'support'. These queues can be logged into by queue members, and those members will also have the ability to pause and unpause themselves.

All configuration will be done in flat files on the system in order to maintain simplicity in configuration.

Adding SIP Devices to Your Server

The first thing we want to do is register a couple of SIP devices to our server. These devices will be our agents that can login and out of the queues we'll create later. Our naming convention will be to use MAC addresses as we want to abstract the concepts of user (agent), device, and extension from each other.

In sip.conf, we add the following to the bottom of our file:

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What we're doing here is creating a [std-device] template and applying it to a pair of peers that we'll register as 0004f2040001 and 0004f2040002; our devices.

Then our devices can register to Asterisk. In my case I have a hard phone and a soft phone registered. I can verify their connectivity by running 'sip show peers'.

Configuring Device State

Next, we need to configure our system to track the state of the devices. We do this by defining a 'hint' in the dialplan which creates the ability for a device subscription to be retained in memory. By default we can see there are no hints registered in our system by running the 'core show hints' command.

We need to add the devices we're going to track to the extensions.conf file under the [default] context which is the default configuration in sip.conf, however we can change this to any context we want with the 'subscribecontext'

Add the following lines to extensions.conf:

Then perform a 'dialplan reload' in order to reload the dialplan.

After reloading our dialplan, you can see the status of the devices with 'core show hints' again.

At this point, create an extension that you can dial that will play a prompt that is long enough for you to go back to the Asterisk console to check the state of your device while it is in use.

To do this, add the 555 extension to the [devices] context and make it playback the tt-monkeys file.

Dial that extension and then check the state of your device on the console.

Aha, we're not getting the device state correctly. There must be something else we need to configure.

In sip.conf, we need to enable 'callcounter' in order to activate the ability for Asterisk to monitor whether the device is in use or not. In versions prior to 1.6.0 we needed to use 'call-limit' for this functionality, but call-limit is now deprecated and is no longer necessary.

So, in sip.conf, in our [std-device] template, we need to add the callcounter option.

Then reload chan_sip with 'sip reload' and perform our 555 test again. Dial 555 and then check the device state with 'core show hints'.

Note that now we have the correct device state when extension 555 is dialed, showing that our device is InUse after dialing extension 555. This is important when creating queues, otherwise our queue members would get multiple calls from the queues.

Adding Queues to Asterisk

The next step is to add a couple of queues to Asterisk that we can assign queue members into. For now we'll work with two queues; sales and support. Lets create those queues now in queues.conf.

We'll leave the default settings that are shipped with queues.conf.sample in the [general] section of queues.conf. See the queues.conf.sample file for more information about each of the available options.

We can then define a [queue_template] that we'll assign to each of the queues we create. These definitions can be overridden by each queue individually if you reassign them under the [sales] or [support] headers. So under the [general]
section of your queues.conf file, add the following.

After defining our queues, lets reload our module.

Then verify our queues loaded with 'queue show'.

Adding Queue Members

You'll notice that we have no queue members available to take calls from the queues. We can add queue members from the Asterisk CLI with the 'queue add member' command.

This is the format of the 'queue add member' command:

The penalty, membername, and state_interface are all optional values. Special attention should be brought to the 'state_interface' option for a member though. The reason for state_interface is that if you're using a channel that does not have device state itself (for example, if you were using the Local channel to deliver a call to an end point) then you could assign the device state of a SIP device to the pseudo channel. This allows the state of a SIP device to be applied to the Local channel for correct device state information.

Lets add our device located at SIP/0004f2040001

Then lets verify our member was indeed added.

Now, if we dial our 555 extension, we should see that our member becomes InUse within the queue.

We can also remove our members from the queue using the 'queue remove' CLI command.

Because we don't want to have to add queue members manually from the CLI, we should create a method that allows queue members to login and out from their devices. We'll do that in the next section.

But first, lets add an extension to our dialplan in order to permit people to dial into our queues so calls can be delivered to our queue members.

Then reload the dialplan, and try calling extension 100 from SIP/0004f2040002, which is the device we have not logged into the queue.

And now we call the queue at extension 100 which will ring our device at SIP/0004f2040001.

We can see the device state has changed to Ringing while the device is ringing.

Our queue member then answers the phone.

And we can see the queue member is now in use.

Then the call is hung up.

And we see that our queue member is available to take another call.

Logging In and Out of Queues

In this section we'll show how to use the AddQueueMember() and RemoveQueueMember() dialplan applications to login and out of queues. For more information about the available options to AddQueueMember() and RemoveQueueMember() use the 'core show application <app>' command from the CLI.

The following bit of dialplan is a bit long, but stick with it, and you'll see that it isn't really all that bad. The gist of the dialplan is that it will check to see if the active user (the device that is dialing the extension) is currently logged into the queue extension that has been requested, and if logged in, then will log them out; if not logged in, then they will be logged into the queue.

We've updated the two lines we added in the previous section that allowed us to dial the sales and support queues. We've abstracted this out a bit in order to make it easier to add new queues in the future. This is done by adding the queue
names to a global variable, then utilizing the extension number dialed to look up the queue name.

So we replace extension 100 and 101 with the following dialplan.

The globals section contains the following two global variables.

So when we dial extension 100, it matches our pattern _1XX. The number we dialed (100) is then retrievable via ${EXTEN} and we can get the name of queue 100 (sales) from the global variable QUEUE_100. We then assign it to the channel variable thisQueue so it is easier to work with in our dialplan.

We then check to see if we've gotten a value back from the global variable which would indicate whether the queue was valid or not.

If ${thisQueue} returns nothing, then we Goto the invalid_queue extension and playback the 'invalid' file.

We could alternatively limit our pattern match to only extension 100 and 101 with the _10[0-1] pattern instead.

Lets move into the nitty-gritty section and show how we can login and logout our devices to the pair of queues we've created.

First, we create a pattern match that takes star (star) plus the queue number that we want to login or logout of. So to login/out of the sales queue (100) we would dial *100. We use the same extension for logging in and out.

We save the value of ${EXTEN:1} to the 'xtn' channel variable so we don't need to keep typing the complicated pattern match.

Now we move into the meat of our login/out dialplan inside the [queueLoginLogout] context.

The first section is initializing some variables that we need throughout the member_check extension such as the name of the queue, the members currently logged into the queue, and the current device peer name (i.e. SIP/0004f2040001).

At this point if there are no members currently logged into our sales queue, we then short-circuit our dialplan to go to the 'q_login' extension since there is no point in wasting cycles searching to see if we're already logged in.

The next step is to finish initializing some values we need within the While() loop that we'll use to check if we're already logged into the queue. We set our ${field} variable to 1, which will be used as the field number offset in the CUT() function.

Now we get to enter our While() loop to determine if we're already logged in.

This is where we check to see if the member at this position of the list is the same as the device we're calling from. If it doesn't match, then we go to the 'check_next' priority label (where we increase our ${field} counter variable). If it does match, then we continue on in the dialplan.

If we continued on in the dialplan, then we set the ${logged_in} channel variable to '1' which represents we're already logged into this queue. We then exit the While() loop with the ExitWhile() dialplan application.

If we didn't match this peer name in the list, then we increase our ${field} counter variable by one, update the ${thisQueueMember} channel variable and then move back to the top of the loop for another round of checks.

And once we exit our loop, we determine whether we need to log our device in or out of the queue.

The following two extensions are used to either log the device in or out of the queue. We use the AddQueueMember() and RemovQueueMember() applications to login or logout the device from the queue.

The first two arguments for AddQueueMember() and RemoveQueueMember() are 'queue' and 'device'. There are additional arguments we can pass, and you can check those out with 'core show application AddQueueMember' and 'core show application RemoveQueueMember()'.

And that's it! Give it a shot and you should see console output similar to the following which will login and logout your queue members to the queues you've configured.

You can see there are already a couple of queue members logged into the sales queue.

Then we dial *100 to logout the active device from the sales queue.

And we can see that the device we loggd out by running 'queue show sales'.

Pausing and Unpausing Members of Queues

Once we have our queue members logged in, it is inevitable that they will want to pause themselves during breaks, and other short periods of inactivity. To do this we can utilize the 'queue pause' and 'queue unpause' CLI commands.

We have two devices logged into the sales queue as we can see with the 'queue show sales' CLI command.

We can then pause our devices with 'queue pause' which has the following format.

Lets pause device 0004f2040001 in the sales queue by executing the following.

And we can see they are paused with 'queue show sales'.

At this point the queue member will no longer receive calls from the system. We can unpause them with the CLI command 'queue unpause member'.

And if you don't specify a queue, it will pause or unpause from all queues.

Of course we want to allow the agents to pause and unpause themselves from their devices, so we need to create an extension and some dialplan logic for that to happen.

Below we've created the pattern patch _0[01]! which will match on *00 and *01, and will *also match with zero or more digits following it, such as the queue extension number.

So if we want to pause ourselves in all queues, we can dial *00; unpausing can be done with *01. But if our agents just need to pause or unpause themselves from a single queue, then we will also accept *00100 to pause in queue 100 (sales), or we can unpause ourselves from sales with *01100.

The following line will determine if we're trying to pause or unpause. This is done by taking the value dialed (e.g. *00100) and chopping off the first 2 digits which leaves us with 0100, and then the :1 will return the next digit, which in this case is '0' that we're using to signify that the queue member wants to be paused (in queue 100).

So we're doing the following with our EXTEN variable.

Which causes the following.

The following two extensions, pause & unpause, are used for pausing and unpausing our extension from the queue(s). We use the PauseQueueMember() and UnpauseQueueMember() dialplan applications which accept the queue name (optional) and the queue member name. If the queue name is not provided, then it is assumed we want to pause or unpause from all logged in queues.

Once we've unpaused ourselves, we use GoSub() to perform some common dialplan logic that is used for pausing and unpausing. We pass three arguments to the subroutine:

  • variable name that contains the result of our operation
  • the value we're expecting to get back if successful
  • the filename to play

And the same method is done for pausing.

Lets explore what happens in the subroutine we're using for pausing and unpausing.

The following line is probably the most complex. We're using the IF() function inside the Playback() application which determines which file to playback to the user.

Those three values we passed in from the pause and unpause extensions could have been something like:

  • ARG3 – unavailable

So when expanded, we'd end up with the following inside the IF() function.

${PQMSTATUS} would then be expanded further to contain the status of our PauseQueueMember() dialplan application, which could either be PAUSED or NOTFOUND. So if ${PQMSTATUS} returned PAUSED, then it would match what we're looking to match on, and we'd then return 'unavailable' to Playback() that would tell the user they are now unavailable.

Otherwise, we'd get back a message saying "not yet connected" to indicate they are likely not logged into the queue they are attempting to change status in.

If ${xtn} is null, then we just go to the end of the subroutine, but if it isn't then we will play back "in the queue" followed by the queue extension number indicating which queue they were (un)paused from.

Queue Variables

Sometimes you may want to retrieve information about a particular queue's state. You can do this by using Queue Variables, and its associated functions. For instance here is a contrived example of how to print a couple variables for the "thisQueue":

Note, QUEUE_VARIABLES needs to be called with a valid queue name, and prior to calling the other queue variable functions in order to ensure retrieval of the correctly associated values for a given queue.


You should now have a simple system that permits you to login and out of queues you create in queues.conf, and to allow queue members to pause themselves within one or more queues. There are a lot of dialplan concepts utilized in this
article, so you are encouraged to seek out additional documentation if any of these concepts are a bit fuzzy for you.

A good start is the doc/ subdirectory of the Asterisk sources, or the various configuration samples files located in the configs/ subdirectory of your Asterisk source code.

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  1. before anything, thanks too much because of your wiki;
    I think that it should be so nice, if we answer the Calls that want to insert info QUEUE, just before that queuing them.

    the problem was that i MOH was playing, but the Callers didn't hear anything,so i do some what like the fallowing change:

    ;add Answer application before queuing calls


    exten => _1XX,n,Answer()
    exten => _1XX,n,Queue(${thisQueue})

    I will be glad to know if i do anything wrong, or not!
    but this change solved my problem very well.

    Best Regards,
    Ali R. Taleghani

    1. Howdy,

      Unless you've not already answered them in the dialplan, you shouldn't have to do that at this point. Are they unanswered, otherwise?

  2. on this wiki, there is no other answer application elsewhere :-/

    could you please lead me to know where should be better, instead of here?

    1. If that's your entry point for a call, then that's a fine place.


  3. Hi everyone,


    we are using a large number of queues and got over 1000 phones registered.

    We now want to hint if there is anyone dial directly or at the queue


    e.g. this is a part our old hints.conf

    exten => 23556117,hint,SIP/23556117&SIP/23556117_q_68

    exten => 13556117,hint,SIP/13556117&SIP/13556117_q_52

    exten => 23556118,hint,SIP/23556118

    exten => 23556122,hint,SIP23/556122



    we now want to dynamically generate the hints like

    exten => _Z.,hint,SIP/${EXTEN}

    but there the queues wouldn't match


    this wont work either

    exten => _Z.,hint,SIP/${EXTEN}!

    couse the provided queue has to be added by hand


    is it possible to provide the wildcard in the description of the hint?