JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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I'm sorry, but can you elaborate further the thing you want in the form? Are you trying to validate the mobile phone number in the form to make sure that only valid numbers are submitted by your customers? If so, you can use our SMS validation widget: http://widgets.jotform.com/widget/sms_confirmation. This widget requires a Twilio account. Kindly check and please let us know if this doesn't answer your question.