How to add a phone number in instant check out

in ,  
Just had a customer phone as they were trying to use instant check out in our Prestashop (version 1.4) but encountered the following problem:
There is no space to enter a phone number
The shop wouldn't complete the order without them entering a phone number.

Solutions for add a phone number in instant check out

  1. In your Back Office > Shipping > Countries menu, find whichever country/countries you need the phone number for. See image.
  2. Click on the edit icon, scroll down and you should see the options below:
  3. If you add 'phone' there and save your options the input field should appear in your checkout