This is the equipment/model ID the discovered ONU reports, letting the admin distinguish, say, a single-port bridge ONU from a 4-port HGU before deciding which line and service profile to assign it. Getting the equipment type right at this discovery stage avoids assigning a profile meant for a different hardware class. For example, seeing an equipment ID that maps to an HGU model tells the admin to assign voice and Wi-Fi-aware profiles rather than a plain bridge profile.