Receiving Digit String Input
You can use built-in “digits” grammar to accept digit strings such as credit card account information. You use the type attribute in a <field> element to select the built-in grammar.
Example Receiving Digit String Input shows how to receive DTMF input for a credit card account number.
<form>
<field name="creditNumber" type="digits">
Please enter your credit card number.
Press the pound key when finished.
<filled>
Your credit card number is
<value expr="creditNumber" class="digits" mode="recorded"/>
<exit namelist="creditNumber"/>
</filled>
</field>
</form>