1. Let's begin, click on the 'Settings' to get started.

2. Now navigate to and select 'Custom Fields'.

3. In the new window, go ahead and click 'Add Field'.

4. From the options, select 'Phone'.

5. Here you can preview your custom field layout.

6. Once you're satisfied, proceed by clicking 'Next'.

7. Input a name for your Field.

8. Select a group by clicking on the corresponding element.

9. Add a placeholder for your field, if needed.

10. Now, choose an object from the provided options.

11. Should you wish to add prefill data, choose a suitable option.

12. For further customization, click 'Additional preferences'.

13. Optionally, customize the unique key in this field.

14. Add a description to summarize your field's purpose.

15. Finally, click 'Save' to finish creating your custom phone field.
