For all our forms, phone number field is causing a issue in reports as users can enter just a single digit, is there is a workaround? to limit the minimum phone number digits?
Will, you can use the mask input feature (Apply Input Masking to a Field in a Form - Marketo Docs - Product Docs) for the phone number field on the form. Make it a text field and by inputting "9999999999" you then require the field to have a maximum of 10 numbers. I do not believe it can enforce a minimum length though.
You can input as many "9" digits necessary, it just enforces that an inputted number cannot have more digits than what you allow.
I have not found a way to mask like you are asking for, which is also disappointing here.
If there were the ability to mask in one of two ways either of ##-###-###-#### or ###-###-#### it would be great, and solve the international issue, however, this is not an option without customization.
If you are a global company though, you will need to take into account Intl Codes and lengths.
See some examples of what you can do at MktoForms2 :: Extended Phone Validation
Obviously you can go down a real rabbit hole in trying to allow user-formatted entries while still trying to detect "obviously" bad formats. That's why usually phone #s are masked to a particular format, though as Josh said this has to be localized.
Here is a test landing page I created:
Can you advise on how I can ensure that the user can NOT submit the form if they input a phone number that is less than 7 digits or more than 13 digits?