AT&T

Any device whose MAC address begins with 80:3A:59 has a network interface built by AT&T. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address.

OUI prefix

80:3A:59

Organization

AT&T

Address

1025 Lenox Park Blvd Atlanta GA US 30319

Source

IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.