Blueworx Voice Response generates "unsupported language" error when running VoiceXML Application

The VXML2 application is of the type:

<vxml version="2.0" xmlns="http://www.w3.org/2001/vxml">
<form>
<field name="key1" type="digits">
         <prompt>
                 <audio scr="PIN.wav" />
         </prompt>
</form>
</vxml>

A test call to such an application generates an error similar to the following:

error.unsupported.language:en: com.ibm.vxi.srvc.UnsupportedLanguageError: en
at com.ibm.wvr.vxml2.DTGrammarProcessorSupport.commitChanges(DTGrammarProcessorSupport.java:314)
       at com.ibm.wvr.vxml2.DTAsrService.commitChanges(DTAsrService.java:128)
        at com.ibm.vxi.intp.VXIContext.collect(VXIContext.java:3253)
        at com.ibm.vxi.intp.VXIContext.collectInput(VXIContext.java:2858)
        at com.ibm.vxi.intp.Efield.exec(Efield.java:220)
        at com.ibm.vxi.intp.FIA.exec(FIA.java:1257)
        at com.ibm.vxi.intp.FIA.collect(FIA.java:739)
        at com.ibm.vxi.intp.FIA.main(FIA.java:536)
        at com.ibm.vxi.intp.FIA.init(FIA.java:418)
        at com.ibm.vxi.intp.FIA.run(FIA.java:227)
        at com.ibm.vxi.intp.VXISession.run(VXISession.java:429)
        at com.ibm.vxi.intp.VXIContext.interpret(VXIContext.java:475)
        at com.ibm.vxi.intp.VoiceBrowser.run(VoiceBrowser.java:570)
        at com.ibm.wvr.vxml2.VXML2BrowserLauncher.waitForCall(VXML2BrowserLauncher.java:1286)
        at com.ibm.wvr.vxml2.DTVoicelet2.run(DTVoicelet2.java:460)
        at java.lang.Thread.run(Thread.java:568)

and the application is terminated.

The problem is due to the default input for <field> in the application being set to voice input. When the voice recognition is not configured, or not available from the Blueworx Voice Response system, the error above occurs.

To use the <field> element in a VoiceXML 2 application without voice recognition, the application needs to be changed to include <property name="inputmodes" value="dtmf"/> after the <vxml> element and before the <field> element for DTMF input.