A knowledge base article about What if I don't have a university supplied smartphone and don't want to use my personal phone? provided by the UC Berkeley IT Service Hub - Knowledge Portal
You don't need a smartphone (iPhone, Android, etc.) to use CalNet 2-Step. While using a smartphone is convenient, you can pick up a Security Key which is a physical device used for multi-factor authentication. These are free of charge for anyone required to do the 2-Step.
You can also generate 10 passcodes at a time using the CalNet Account Manager.