The supplier is the entity who you purchased eligible devices from. If you purchased the device directly from Apple using a purchase order (PO), then you would enter your Apple customer number as your supplier using the Apple (Direct) option. If you purchased your device through a participating Apple Authorized Reseller or carrier, then you would add them as a supplier to your account by entering their Reseller ID using the Reseller option. Each supplier needs to be added only once to your account profile.