Which company owns MAC address prefix 20:5F:3D?

MAC address prefix 20:5F:3D is registered to Adtran Inc in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 20:5F:3D has a network interface built by Adtran Inc.

What is the OUI 20:5F:3D?

20:5F:3D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Adtran Inc. It covers every address from 20:5F:3D:00:00:00 to 20:5F:3D:FF:FF:FF, or 16,777,216 addresses in total. It is also written 20-5F-3D.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 20:5F:3D:00:00:00 that is 20:5F:3D — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is Adtran Inc located?

Adtran Inc is listed at Victory House, Vision Park, Chivers Way, Histon Cambridge GB CB24 9ZR in the IEEE OUI registry entry for 20:5F:3D. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Adtran Inc own?

Adtran Inc holds 15 OUI prefixes in the IEEE registry, of which 20:5F:3D is one. A device made by Adtran Inc could carry a MAC address from any of them.

Adtran Inc

MAC address prefix 20:5F:3D is registered to Adtran Inc in the IEEE OUI registry. Any device whose MAC address begins with 20:5F:3D has a network interface built by Adtran Inc. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 20:5F:3D:00:00:00 to 20:5F:3D:FF:FF:FF.

OUI prefix: 20:5F:3D
Hyphen form: 20-5F-3D
MAC range: 20:5F:3D:00:00:00 – 20:5F:3D:FF:FF:FF
Addresses in block: 16,777,216
Organization: Adtran Inc
Address: Victory House, Vision Park, Chivers Way, Histon Cambridge GB CB24 9ZR
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.

Other prefixes from Adtran Inc

Adtran Inc holds 15 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (3)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2019-07-04Assigned to "Cambridge Communication Systems Ltd"
archived source →
2023-07-11Renamed from "Cambridge Communication Systems Ltd" to "Adtran Inc"
archived source →
2026-07-17Assigned to "Adtran Inc"

Nearby in the registry

The prefixes assigned immediately before and after 20:5F:3D:

FAQ

Which company owns MAC address prefix 20:5F:3D?: MAC address prefix 20:5F:3D is registered to Adtran Inc in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 20:5F:3D has a network interface built by Adtran Inc.
What is the OUI 20:5F:3D?: 20:5F:3D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Adtran Inc. It covers every address from 20:5F:3D:00:00:00 to 20:5F:3D:FF:FF:FF, or 16,777,216 addresses in total. It is also written 20-5F-3D.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 20:5F:3D:00:00:00 that is 20:5F:3D — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is Adtran Inc located?: Adtran Inc is listed at Victory House, Vision Park, Chivers Way, Histon Cambridge GB CB24 9ZR in the IEEE OUI registry entry for 20:5F:3D. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Adtran Inc own?: Adtran Inc holds 15 OUI prefixes in the IEEE registry, of which 20:5F:3D is one. A device made by Adtran Inc could carry a MAC address from any of them.