Custom fields in tickets are used to gather additional information about a ticket, requester or client. You can add custom fields to your tickets for agents to have a better understanding and context of an issue.
Navigate to Settings > Advanced Customization > Custom Fields
Choose Tickets, Clients or Requesters
Name and describe the Custom Fields on the ‘Create Custom Ticket fields’ page.
Select the type of field you wish to create.
For example, Text fields for entering names, multi-line text for adding descriptive details, and Numbers for entering phone numbers, as shown above. Then configure the visibility of the custom field and hit Save once you're done.