Which company owns MAC address prefix A4:EF:52?

MAC address prefix A4:EF:52 is registered to Telewave Co., Ltd. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:EF:52 has a network interface built by Telewave Co., Ltd..

What is the OUI A4:EF:52?

A4:EF:52 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Telewave Co., Ltd.. It covers every address from A4:EF:52:00:00:00 to A4:EF:52:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-EF-52.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in A4:EF:52:00:00:00 that is A4:EF:52 — 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 Telewave Co., Ltd. located?

Telewave Co., Ltd. is listed at A-203, SK Twintech Tower Seoul KR 153-773 in the IEEE OUI registry entry for A4:EF:52. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Telewave Co., Ltd.

MAC address prefix A4:EF:52 is registered to Telewave Co., Ltd. in the IEEE OUI registry. Any device whose MAC address begins with A4:EF:52 has a network interface built by Telewave Co., Ltd.. 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 A4:EF:52:00:00:00 to A4:EF:52:FF:FF:FF.

OUI prefix: A4:EF:52
Hyphen form: A4-EF-52
MAC range: A4:EF:52:00:00:00 – A4:EF:52:FF:FF:FF
Addresses in block: 16,777,216
Organization: Telewave Co., Ltd.
Address: A-203, SK Twintech Tower Seoul KR 153-773
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.

2016-07-29Assigned to "Telewave Co., Ltd."
archived source →
2026-07-17Assigned to "Telewave Co., Ltd."

Nearby in the registry

The prefixes assigned immediately before and after A4:EF:52:

FAQ

Which company owns MAC address prefix A4:EF:52?: MAC address prefix A4:EF:52 is registered to Telewave Co., Ltd. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:EF:52 has a network interface built by Telewave Co., Ltd..
What is the OUI A4:EF:52?: A4:EF:52 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Telewave Co., Ltd.. It covers every address from A4:EF:52:00:00:00 to A4:EF:52:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-EF-52.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in A4:EF:52:00:00:00 that is A4:EF:52 — 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 Telewave Co., Ltd. located?: Telewave Co., Ltd. is listed at A-203, SK Twintech Tower Seoul KR 153-773 in the IEEE OUI registry entry for A4:EF:52. This is the address the organization registered with the IEEE, which may differ from its current operating address.