Using Duo without Cellular Service or While Traveling

Duo provides offline authentication options for times when you lack cell service or when using multi-factor authentication (MFA) could cause you to incur extra cellphone charges, such as when you are traveling internationally.

NOTE: In order to take advantage of the options below, be sure to register your device(s) for use with your MFA account (including, if applicable, downloading and installing the Duo Mobile App on your smartphone) before you begin your travel.

Duo Mobile App (Smartphones and Tablets)

You can request single-use passcodes directly from the Duo Mobile app, even when your mobile device is in airplane mode or lacks cell service.

  • Simply open the app and tap the Passcode button. Depending on your device, this button may say Generate Passcode or Generate Token Code. It may also simply contain an image of a key.
  • Enter the code provided in the Passcode field of the Duo verification screen.

Text Message

If you do not have the Duo Mobile App installed on a mobile device, you can request a batch of passcodes to be sent via text message to your cellphone before you depart for your travel.

  • From the Duo verification screen, press Send SMS passcodes. You will receive ten single-use codes via text message, which will allow you to authenticate up to ten times during your travel.

You will need to request the passcodes before you leave, or while in an area with cell service, as you will need a cell connection to receive the text message on your phone.

  • You may request additional batches of passcodes while in areas with cell service (your carrier’s roaming or international texting rates will apply). Requesting a new batch of passcodes will invalidate any unused codes from the previous batch.


  • Public wireless hotspots generally provide unsecure networks that could allow others to access your information. Make sure to use the USC VPN whenever you connect to USC systems via a public wireless connection, including hotel, convention center, and cafĂ© wireless networks. Use of a VPN will protect your personal information by encrypting it over open networks. For more information about VPN, see
  • If you do not have access to a smartphone or tablet that you can use for MFA while traveling, please contact the ITS Customer Support Center for assistance.