Which company owns MAC address prefix 38:14:1B?

MAC address prefix 38:14:1B is registered to Secure Letter Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 38:14:1B has a network interface built by Secure Letter Inc..

What is the OUI 38:14:1B?

38:14:1B is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Secure Letter Inc.. It covers every address from 38:14:1B:00:00:00 to 38:14:1B:FF:FF:FF, or 16,777,216 addresses in total. It is also written 38-14-1B.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 38:14:1B:00:00:00 that is 38:14:1B — 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 Secure Letter Inc. located?

Secure Letter Inc. is listed at 223, Yeoksam-ro Gangnam-gu Seoul KR 06224 in the IEEE OUI registry entry for 38:14:1B. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Secure Letter Inc.

MAC address prefix 38:14:1B is registered to Secure Letter Inc. in the IEEE OUI registry. Any device whose MAC address begins with 38:14:1B has a network interface built by Secure Letter 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 38:14:1B:00:00:00 to 38:14:1B:FF:FF:FF.

OUI prefix: 38:14:1B
Hyphen form: 38-14-1B
MAC range: 38:14:1B:00:00:00 – 38:14:1B:FF:FF:FF
Addresses in block: 16,777,216
Organization: Secure Letter Inc.
Address: 223, Yeoksam-ro Gangnam-gu Seoul KR 06224
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.

2023-07-11Assigned to "Secure Letter Inc."
archived source →
2026-07-17Assigned to "Secure Letter Inc."

Nearby in the registry

The prefixes assigned immediately before and after 38:14:1B:

FAQ

Which company owns MAC address prefix 38:14:1B?: MAC address prefix 38:14:1B is registered to Secure Letter Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 38:14:1B has a network interface built by Secure Letter Inc..
What is the OUI 38:14:1B?: 38:14:1B is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Secure Letter Inc.. It covers every address from 38:14:1B:00:00:00 to 38:14:1B:FF:FF:FF, or 16,777,216 addresses in total. It is also written 38-14-1B.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 38:14:1B:00:00:00 that is 38:14:1B — 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 Secure Letter Inc. located?: Secure Letter Inc. is listed at 223, Yeoksam-ro Gangnam-gu Seoul KR 06224 in the IEEE OUI registry entry for 38:14:1B. This is the address the organization registered with the IEEE, which may differ from its current operating address.