Phone No. In Contact Us Form

[phone your-phone-number]

Is not available in Contact From 7 tag syntax. See ??tag sytax

You probably want to try something like this ?

[number* your-number]

* – indicates a required field. Also see number field

Remember to add [your-number] to your mail section where you want to display the values entered by the user.

Contact Form 7 supports telephone number field. See https://contactform7.com/text-fields/#tel