The link from a ServiceNav company to the equivalent company in the extended ticketing system is a prerequisite for opening tickets from ServiceNav.
Prerequisite: Integration with your external ticketing system is in place
Changing the Company Master Record
Go to the menu "Organization" on the company to be linked and click on "Edit"
There is a "CRM link" field. Enter the name of the company (and/or site depending on the integration) in the field to start a search in the external ticketing system.
Choose the company and validate.