Manage sign in options: https://mysignins.microsoft.com/security-info
What happens if you forget your mobile at home, or your mobile is not working, or you are at home, ... or whatever. Our recommendation is to configure several additional ways:
office phone number (if you don't have access to your mobile phone)
personal mobile phone number (if you're not in your office)
if exist: classical phone from at home (if your mobile is broken)
Self-Service Portal: https://support.uzh.ch/
E-Mail: support@zi.uzh.ch
More Information: https://www.zi.uzh.ch/en/support.html
And for the next time: remember to setup a second way of authentication, before you loose the first one