Sometimes I need to get user's mobile phone in my HTML form, and after that user will receive account information and refer code by text message. I want to ask you what is the best way to give warning to user that, "your number is important for us!" and should be yours?

In my opinion this is better done with just an alert near the field. But I don't know probably the form should be two steps, first user input number then receive a refer code by text message and in the step two I will get the refer code to be sure that the number is real.

  • Easiest and most reliable way is to use the code that you mention. Dec 15, 2016 at 15:02

4 Answers 4


If the user is in no need to put his real number to use the app/web I don't think it really matters the exact phrasing, being honest and nearer is probably better but you might still get fake numbers. You can:

  • Penalize users that don't enter the correct number, don't letting them proceed or make full use of the app until they enter a valid number
  • Reward users that do enter the correct number, showing in the web/community that those are trustful users.

If the number is not needed for the user to proceed, then if he wants to give a fake number he will lie or not independently of the text next to the field.


  1. Give true number
  2. Give fake number


  • No difference for them (see the upper note on trustfulness in a community); fake information for you

If the phone number is required for the app to work, let the user know explicitly that the phone number is needed (and possibly don't let him proceed without entering one). The user doesn't have the need to lie as that would be the same as not completing the form. So this way you assure you have the correct number, but there might probably be some users who won't complete the form.


  1. Give true number
  2. Don't give any number


  • Continue or not in the app for them; only correct information for you, but possibly less users.

More important you should signify why a phone number is needed then provide visual confirmation as to how the phone number will be used.

Will user be getting a phone call in 24 hours? Or is it just for verification purposes? User needs to know and be confident their phone number will be treated with respect.


Using a code to verify the validity of the number will result in trustful data but if you make it mandatory it will cause a lot of friction what might lead to fewer people completing that form.

I like the idea of rewarding those who give a valid phone number. If you do that you have to let the user know of that reward beforehand. I like this approach better than the penality approach because I prefer that the user is driven by a positive emotion and not by a negative one.

At my working place we use a custom tooltip on input focus to let the user know that by giving real information we will be able to give them a better service. That's enough for us. And people do give they real numbers specially if they know that you won't be bothering them or selling their information.


I think the best way is write a label "Provide your contact number" and put a small info icon on which OnHover it will display the information of What is the user of this phone number.

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