Users unable to fill in the cell phone field

We have had several users who are unable to submit the form due to an incomplete cell phone filed. The users say that they are filling in the field and when they fax their form to us, they have in fact filled in the field.  Please let me know how to fix this problem.

I examined your form and noticed that you are using the number field for the phone numbers.

We do have a field specialized for phone numbers, and it provides you with the ability to set a mask to make sure the form users enter their phone numbers in the specific way that you would like them to, significantly reducing the margin of error as a result.

I created a sample form with a phone number field, and I set its mask to something similar to what you're currently using. If you would like to clone it, here it is: https://form.jotform.com/63535322255957

I also created an animation for you to see step by step how I configured the phone number field in that sample form, so you can easily replicate that into your form:

Please let us know if you need further assistance or have more questions.