How do USB micro-B phones determine the host?
You're confused. USB Mini-A, Mini-B, Micro-A, and Micro-B plugs -- as well as the ports they plug into -- all have five pins, including one ID pin. They are all electrically identical.



The only difference between Micro-B and Micro-AB is the physical shape of the port -- a USB Micro-A connector cannot be inserted into a Micro-B port. As Micro-A (as well as Mini-A) connectors are almost never seen, this has no effect in practice.