Single DTMF Hotword Barge-in

Blueworx Voice Response supports hotword barge-in for DTMF keys in accordance with the VoiceXML 2.0 specification when using an external MRCP speech server for DTMF recognition (enabled by using a <property name="com.ibm.dtmf.useexternaldetection" value="true"/> setting in the application).

When using the default DTMF detection method, where Blueworx Voice Response handles the DTMF recognition internally, it is possible to use single key DTMF hotword barge-in. This allows for a single DTMF key, drawn from a pre-defined list, to barge-in a prompt where other DTMF keys are ignored.

The prompt must have barge-in enabled, with a hotword barge-in type:

 <prompt bargein="true" bargeintype="hotword">

To specify the DTMF keys that can hotword barge-in, a property needs to be set with the name “com.bvr.dtmflist” along with a value of the accepted DTMFs. The following example enables the DTMF keys 1, 2 and * for hotword barge-in:

 <property name="com.bvr.dtmflist" value="12*"/>

A DTMF grammar must also be active during this prompt that lists a superset of the DTMF keys listed in the property “com.bvr.dtmflist”. The following example enables the DTMF keys 1, 2, 5, 8, * for the prompt:

 <grammar version="1.0" mode="dtmf" root="example">
         <rule id="example">
                 <item>
                 <one-of>
                     <item>1</item>
                     <item>2</item>
                     <item>5</item>
                     <item>8</item>
                     <item>*</item>
                 </one-of>
                 </item>
         </rule>
 </grammar>

Here we can see that 1, 2 and * is set in both the “com.bvr.dtmflist” property and the active DTMF grammar.

Note: The “com.bvr.dtmflist” property is the only active list of DTMFs during the prompt. The grammar is the only active list of DTMFs after the prompt. During the prompt, the only DTMFs that result in a barge-in are those specified by the “com.bvr.dtmflist” property. The grammar after the prompt can result in a NOINPUT, NOMATCH or MATCH event being thrown.