Validate at least one phone number & the numbers themselves?

Validate at least one phone number & the numbers themselves?

Hi have a form with three fields for home phone, work phone & mobile phone. 

I've got jquery to validate that the numbers entered are the right format, i.e. using the following with custom methods for the phoneUK etc.

  1. x_HomeTel: {required: true, phoneUK: true},
  2. x_WorkTel: {required: true, workUK: true  },
  3. x_MobileTel: {required: true, mobileUK: true  },

The thing is I only need one of these numbers. I have been trying *all day* to try and get this to work but no joy. I know I need to group them somehow but can't figure it out.

I want it so I get a single message if all fields are left empty and then if a field does have an entry then it's validated to ensure its a number. Any help much appreciated!