<Callback/>

Introduction to <Callback> Tag in Opentact XML

The <Callback> tag in Opentact XML plays a crucial role in dynamically obtaining call flow information from a specified URL. This powerful feature allows users to customize the call handling process by fetching the call flow XML remotely.

How <Callback> Works:

When included in a Call Control XML, the <Callback> tag is used to define the URL from which Opentact should retrieve the call flow XML. This URL typically points to an endpoint that generates and returns the desired call flow instructions.

Example Usage:

<Callback url="https://api.opentact.org/rest/call_flow" />

In this example, Opentact will make a request to the specified URL (https://api.opentact.org/rest/call_flow) to fetch the call flow XML. The retrieved XML will then be processed for call handling.

Handling Errors:

The content within the <Callback> tag is primarily focused on error handling scenarios. If, for any reason, Opentact encounters issues fetching or parsing the response from the specified URL, it will execute the defined error block within the <Callback>.

Example Error Handling:

<Callback url="https://api.callify.io/opentact/callflow">
    <Error>
        <Say text="An error occurred"/>
        <Hangup/>
    </Error>
</Callback>

In this scenario, if an error occurs during the callback process, Opentact will say "An error occurred" and subsequently hang up the call.

Parameters:

The <Callback> tag can include various parameters, influencing how Opentact interacts with the specified URL. These parameters ensure flexibility and customization in the call flow retrieval process.

The <Callback> XML tab has the following parameters:

Tag Name	Required	Description
url	YES	This is the URL that Opentact will query to obtain the Dialplan XML.
body	NO	Default is false. If set to true, Opentact will include Call Control APP data in the query's body.
timeout	NO	This is the max time before Opentact will time out. If no response is received within the timeout value, Opentact will execute the <Error> block.
tag	NO	If specified, this tag value will be sent to the callback url in the tag field.
method	YES	Thid value must be one of : "POST", "GET", "PATCH" and "DELETE"

When Opentact trigger an outbound query to the callback URL, the following fields will be included:

Field Name	Description
call	Call UUID
sca	Call Control APP UUID
state	State of the Call. Most likely it is "live"
from	The caller ID of the call
tn	The number being called to
tag	This is the tag specified in the xml.