- If you are taking out a subscription to the ISSN portal for the first time, please complete the form available on the Extranet. Please contact the Sales Department for a personalised estimate attuned to your needs: click on the tab “Discover ISSN Services” or on the button “Contact” in the footer, fill in the form and send it by clicking on the button “Submit”. The ISSN International Centre will then set up the subscription conditions on the Extranet, and inform you by email.