A registered cellular device is a mobile device that uses cellular service, like a smartphone or iPad.

We need a registered cellular device (RCD) listed in your profile. If there's not a registered device on file, you won't be able to use many of the features and services for digital banking. Those features include, but aren't limited to:

• Mobile banking: Requires a mobile device to access. 
• Money movement services: Zelle, internal and external transfers, etc.
• Updating your profile: Address or phone number changes, manage username and password.
• DIY services: Manage account alerts, manage Shared Access users, lock or unlock your card. 

See also: What digital banking tools and features do you offer? and How do I establish a registered cellular device on my profile?