A Global Entry card can be activated on the Web portal GOES or by calling the customer service hotline. You must have your card on hand in order to complete the activation process.
In order to apply for the Global Entry program through U.S. Customs and Border Protection at the Department of Homeland Security, you must create an account on the online portal GOES and schedule an in-person interview. Following the interview and acceptance into the program, you will receive your physical Global Entry card in the mail, which must be activated online or by calling the customer service line.
To activate online, you must have the physical card on hard. First, go to the GOES Web portal at GOES-App.CBP.DHS.gov, and log onto your GOES account. Then click on the "Activate Membership Card" option on the homepage under the "Program Membership" section. Once on this page, you are required to enter the card's PASSID and security code and click next.
If there are any problems activating the card, calling the GOES customer support line is another option. The customer support line hours are Monday through Friday, 9 a.m. to 4 p.m. Eastern Standard Time, and the numbers are 855-873-4637 and 202-325-8060 as of June 2015.