TwiML™ Voice: <Enqueue>
The <Enqueue> verb enqueues the current call in a call queue. Enqueued calls wait in hold music
until the call is dequeued by another caller via the <Dial> verb or transferred out of the queue via
the REST API or the <Leave> verb.
The <Enqueue> verb will create a queue on demand, if the queue does not already exist. The default maximum length of the queue is 100. This can be modified using the
REST API.
<Enqueue> allows you to specify a named queue that already exists by placing the queue name between <Enqueue>'s opening and closing tags. The queue name must be 64 characters or less in length. If the named queue hasn't yet been created, Twilio will create one with the queue name included within <Enqueue>'s opening and closing tags.
Verb Attributes
The <Enqueue> verb supports the following attributes that modify its behavior:
| Attribute Name | Allowed Values | Default Value |
|---|---|---|
| action | relative or absolute URL | none |
| method | GET, POST | POST |
| waitUrl | relative or absolute URL | default classical playlist |
| waitUrlMethod | GET, POST | POST |
| workflowSid | TaskRouter Workflow Sid | none |
action
The action attribute takes an absolute or relative URL as a value.
A request is made to this URL when the call leaves the queue, describing the dequeue reason and details
about the time spent in the queue, which are described below. In the case where a call is dequeued due to
a REST API request or the <Leave> verb, the action URL is requested right away. In the case where a call
is dequeued via the <Dial> verb, the action URL is hit once when the bridged parties disconnect.
If no action is provided, Twilio will fall through to the next verb in the document, if any.
Request Parameters
Twilio passes the following parameters in addition to the standard TwiML Voice request parameters with its request to the action URL:
| Parameter | Description |
|---|---|
QueueResult |
The final result of the enqueued call. See queue result values below for details. |
QueueSid |
The SID of the queue. This is only available if the call was actually enqueued. |
QueueTime |
The time the call spent in the queue. This is only available if the call was actually enqueued. |
QueueResult values
The following values represent the result of an attempt to enqueue a caller.
| Value | Description |
|---|---|
bridged |
The call was dequeued and bridged to the dequeuer. |
bridging-in-process |
Twilio has been instructed to bridge the enqueued party. |
error |
The TwiML contained an error, either in the <Enqueue> verb itself or in the TwiML retrieved from a waitUrl. Check the App Monitor. |
hangup |
The enqueued caller hung up before connecting to a dequeued call. |
leave |
The enqueued caller exited the queue via the <Leave> verb. |
redirected |
While in the queue, the call was redirected out of the queue, typically by a REST API request. |
redirected-from-bridged |
The queued and then successfully bridged session was transferred out. |
queue-full |
The targeted queue was full, thus the enqueue attempt was rejected. |
system-error |
The Twilio system malfunctioned during the enqueue process. This can happen if a caller hangs up before being fully enqueued. |
method
The method attribute specifies the HTTP method Twilio uses when sending a request to the action URL. takes the value GET or POST. POST is the default value.
waitUrl
The waitUrl attribute specifies a URL pointing to a TwiML document containing TwiML verbs that will be executed while the caller is waiting in the queue.
Once TwiML document located at the waitUrl runs out of verbs to execute, Twilio re-requests the waitUrl. This loops the hold music indefinitely. The <Redirect> verb can be used for multiple TwiML document call flows, but a call will always return to the waitUrl once there is no TwiML left to execute.
The following verbs are supported in the TwiML document located at the waitUrl:
| Verb | Description |
|---|---|
| <Play> | Plays a file to the caller. |
| <Say> | Say something to the caller using Twilio text-to-speech. |
| <Pause> | Pauses for a specified duration. |
| <Hangup> | Hangs up the call and thereby leaving the queue and ending the call. |
| <Redirect> | Redirect to another TwiML document. |
| <Leave> | Makes the current call leave the queue, but doesn't hang up the call. Execution proceeds with the next verb after the '<Enqueue>' verb. |
| <Gather> | Collects digits that a caller enters into his or her telephone keypad. NOTE: The only valid value for <Gather>'s input attribute is dtmf when <Gather> is returned in an <Enqueue> waitUrl; the speech value for the input attribute is not accepted. |
Request Parameters
Twilio will pass the following parameters in addition to the standard TwiML Voice request parameters with its request to the 'waitUrl' URL:
| Parameter | Description |
|---|---|
QueuePosition |
The current queue position for the enqueued call. |
QueueSid |
The SID of the Queue that the caller is in. |
QueueTime |
The time in seconds that the caller has been in the queue. |
AvgQueueTime |
An average of how long the current enqueued callers have been in the queue in seconds. |
CurrentQueueSize |
The current number of enqueued calls in this queue. |
MaxQueueSize |
The maximum number of enqueued calls for this queue. |
waitUrlMethod
The waitUrlMethod attribute specifies the HTTP method Twilio uses when making a request to the waituUrl. Allowed values are GET or POST. The default value is POST.
workflowSid
The workflowSid attribute tells Twilio to create a new TaskRouter Task to represent this call and specifies the ID of the desired Workflow to handle it.
If workflowSid is specified, it is not necessary to specify a name for the Queue to place the call in. When a Worker is identified to handle the call it can be dequeued and connected using the dequeue assignment instruction.
Nouns
The "noun" of a TwiML verb is the nested content of the verb that's not a verb itself; it's the information the verb acts upon. These are the nouns for <Enqueue>:
| Noun | Description |
|---|---|
<Task> |
The attributes to be set for the newly created task, formatted as JSON |
You can find more information and examples on how to use <Task> on the TaskRouter TwiML Integration page.
Examples
Example 1: Simple Enqueue
This TwiML document tells Twilio to fetch the wait-music.xml TwiML document and execute it while the caller is in the queue:
The wait-music.xml TwiML document plays some nice hold music:
Hints and Advanced Uses
- You can use the parameters on the
waitUrlrequest to<Say>back to the caller what his or her queue position is and how long he or she can expect to wait.
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