[yayachiken]

Then we are just talking about two different things.

On ISP level, routing tables are built via BGP. BGP needs Autonomous Systems (AS) as organization unit to work. If you are not an AS you are never a peer as you are not on equal footing.

As a rule of thumb, if your edge router has a default route set, we are very likely talking about different scales.

[direwolf20]

ISPs are encouraged to — but rarely do — use private ASNs with single–homed BGP customers.