Free VoiceXML Resource by C.a.T.S.

<www.vxml.co.za>

<training>

<voicexml tutorial>

DTMF Grammars

In order to switch off the voice recognition mode and force the VoiceXML browser to only accept DTMF input opposed to voice, the following can be added to the VoiceXML document:

<property name="inputmodes" value="dtmf" />

The placing of the property within the context of the VoiceXML document is as follow:

<?xml version="1.0" encoding="iso-8859-1"?>
	<!DOCTYPE vxml PUBLIC "-//W3C//DTD VOICEXML 2.1//EN" "http://www.w3.org/TR/voicexml21/vxml.dtd">
		<vxml version="2.1" xmlns="http://www.w3.org/2001/vxml" xml:lang="en-GB">
		<property name="inputmodes" value="dtmf" />
		<meta http-equiv="expires" content= "Sun, 15 Apr 2007 12:00:00 GMT"/> 
		<meta name="GENERATOR" content="IBM WebSphere Voice Toolkit" />

The shorthand for incorporating DTMF grammar in a VoiceXML document is as follow:

<menu>
  <property name="inputmodes" value="dtmf"/>
  	<prompt>
  		 For option one press 1, For option two press 2, For option three press 3.
  </prompt>
  		<choice dtmf="1" next="#option_one"/>
  			<choice dtmf="2" next="#option_two"/>
  				<choice dtmf="3" next="#option_three"/>
</menu>

Herewith an example of a complete application with the DTMF shorthand example:

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE vxml PUBLIC "-//W3C//DTD VOICEXML 2.1 WVS//EN" "vxml21-0728.dtd">
<vxml version="2.1" xmlns="http://www.w3.org/2001/vxml"
	xml:lang="en-AU">
	<meta name="GENERATOR" content="IBM WebSphere Voice Toolkit" />
	<!-- Place Content Here -->
<menu>
  <property name="inputmodes" value="dtmf"/>
  	<prompt>
  For option one press 1, For option two press 2, For option three press 3.
  	</prompt>
  		<choice dtmf="1" next="#option_one"/>
  			<choice dtmf="2" next="#option_two"/>
  				<choice dtmf="3" next="#option_three"/>
</menu>

	<form id="option_one">
		<block>
			<prompt>
			Hi, This is option one!
			</prompt>
		</block>
	</form>
	
	<form id="option_two">
		<block>
			<prompt>
			Hi, This is option two!
			</prompt>
		</block>
	</form>
	
	<form id="option_tree">
		<block>
			<prompt>
			Hi, This is option three!
			</prompt>
		</block>
	</form>
</vxml>

A general DTMF grammar which can be included in the main VXML document can look as follow:

<grammar mode="dtmf" version="1.0" root="gram">
	<rule id="gram">
		<one-of>
			<item> 1 </item>
			<item> 2 </item>
			<item> 3 </item>
			<item> 4 </item>
			<item> 5 </item>
			<item> 6 </item>
			<item> 7 </item>
			<item> 8 </item>
			<item> 9 </item>
			<item> 0 </item>
		</one-of>
	</rule>
</grammar>

Cases where a DTMF string needs to be captured, are when a numeric password or a contact number must be received. In these cases the application can be told what length of input to expect. However, it does cause the application to be more robust if a caller is requested to enter a termination key. For example, "please enter your mobile number and press hash when done", "please enter your 4 digit password and press hash when done", "record your message after the tone and press hash when done".

In the example below 'star' is specified as the termination key:

<property name="termchar" value="*"/>

In the final example, the DTMF grammar code is displayed within a working example of code:

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE vxml PUBLIC "-//W3C//DTD VOICEXML 2.1 WVS//EN" "vxml21-0728.dtd">
<vxml version="2.1" xmlns="http://www.w3.org/2001/vxml" xml:lang="en-AU">	
	<property name="inputmodes" value="dtmf"/>
	<form id="welcome">
		<block>
			<audio src="welcome.wav" maxage="0">
				Welcome to the Fast Food Store.
			</audio>
</block>	
		<field name="option">
			<property name="termchar" value="*"/>
			<grammar mode="dtmf" version="1.0" root="gram">
				<rule id="gram">
					<one-of>
						<item> 1 </item>
						<item> 2 </item>
						<item> 3 </item>
					</one-of>
				</rule>
			</grammar>
				<prompt>
To check your order status press one, for delivery press two, to test the internet press three. 
</prompt>
			<filled>
				<if cond="option == 1">
					<goto next="#ordercheck"/>
				</if>
				<if cond="option == 2">
					<goto next="#mobilenum"/>
				</if> 
				<if cond="option ==3">
				<goto next="#internet"/>
				</if>
			</filled>
		</field>
	</form>
 
<form id="ordercheck">
<block><prompt> Do something here! </prompt></block>
</form>
<form id="mobilenum">
<block><prompt> Do something here! </prompt></block>
</form>
<form id="internet"> 
<block><prompt> Do something here! </prompt></block>
</form>

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