Which company owns MAC address prefix 40:05:89?

MAC address prefix 40:05:89 is registered to T-Mobile, USA in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:05:89 has a network interface built by T-Mobile, USA.

What is the OUI 40:05:89?

40:05:89 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to T-Mobile, USA. It covers every address from 40:05:89:00:00:00 to 40:05:89:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-05-89.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 40:05:89:00:00:00 that is 40:05:89 — 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 T-Mobile, USA located?

T-Mobile, USA is listed at 3625 132nd Ave SE BELLEVUE WA US 98006 in the IEEE OUI registry entry for 40:05:89. This is the address the organization registered with the IEEE, which may differ from its current operating address.

T-Mobile, USA

MAC address prefix 40:05:89 is registered to T-Mobile, USA in the IEEE OUI registry. Any device whose MAC address begins with 40:05:89 has a network interface built by T-Mobile, USA. 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 40:05:89:00:00:00 to 40:05:89:FF:FF:FF.

OUI prefix: 40:05:89
Hyphen form: 40-05-89
MAC range: 40:05:89:00:00:00 – 40:05:89:FF:FF:FF
Addresses in block: 16,777,216
Organization: T-Mobile, USA
Address: 3625 132nd Ave SE BELLEVUE WA US 98006
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.

Assignment history (2)

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

2020-03-21Assigned to "T-Mobile, USA"
archived source →
2026-07-17Assigned to "T-Mobile, USA"

Nearby in the registry

The prefixes assigned immediately before and after 40:05:89:

FAQ

Which company owns MAC address prefix 40:05:89?: MAC address prefix 40:05:89 is registered to T-Mobile, USA in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:05:89 has a network interface built by T-Mobile, USA.
What is the OUI 40:05:89?: 40:05:89 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to T-Mobile, USA. It covers every address from 40:05:89:00:00:00 to 40:05:89:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-05-89.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 40:05:89:00:00:00 that is 40:05:89 — 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 T-Mobile, USA located?: T-Mobile, USA is listed at 3625 132nd Ave SE BELLEVUE WA US 98006 in the IEEE OUI registry entry for 40:05:89. This is the address the organization registered with the IEEE, which may differ from its current operating address.