Phone Validation with custom Error Message

Please check the link’s phone number validation

I use the same app Woofunnels, but i can’t do the coding for it. even plug ins dont work.

Please help me , i have a few knowledge about coding.

• This topic was modified 5 years, 2 months ago by Jan Dembowski. Reason: Moved to Fixing WordPress, this is not an Developing with WordPress topic

The page I need help with: [log in to see the link]