You can get provider-aggretable (PA) IP addresses from your ISP, but they can only be used with that ISP. You can also get provider-independent (PI) addresses, which you can use and move between ISPs with BGP. If they're using Zayo and Level 3 at the same time, you would need PI-IPs that you can move to the other ISP when one ISP is down.

Or, another option is that they're doing CGNAT on all of their client traffic.