For some of your mobile form's fields it makes sense to have a numeric keyboard show up when users go to enter data into it. For example, if you have a field that is used to collect a customer's zip code that is numeric only, you will always want to enter in numerals. So the default keyboard should be Numeric (instead of Alpha).
You can can configure whether the default keyboard for a field is Alpha or Numeric through the Template Editor. Select the field and in its Properties menu on the bottom left corner of the Editor screen go to the Keyboard setting and you will be able to switch the default option there.
By default, the Keyboard setting is set to 'Alpha.' To change this, simply select the 'Numeric' option.
Note: When working in the Alpha Keyboard, you will always have the option to toggle between alpha and numeric keys. However if your choose the Numeric Keyboard as the default, it will ONLY support numerics (no toggle to Alpha option).