Like spambait throwaway email accounts, but visible to the world indefinitely. Shouldn't use with any service that allows account reset through SMS alone, or who has your real identity or payment info. Think: logins you would put on BugMeNot
Also:
https://sms-hero.com
https://textverified.com/free
[other paid services exist]
Multi-factor authentication keeps your accounts secure. You can use Apple’s authenticator app with iCloud Keychain to make managing your codes easy.
another cross-platform TOTP authenticator
Apple-only. Previously well regarded, but suddenly changed hands suspiciously.
https://github.com/raivo-otp/marketing-website/pull/22
TOTP app, multi-platform including Apple/iPhone
not sure if there's any kind of attendance record that can be used to attest for CPE
