Which company owns MAC address prefix 58:21:E9?

MAC address prefix 58:21:E9 is registered to TWPI in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 58:21:E9 has a network interface built by TWPI.

What is the OUI 58:21:E9?

58:21:E9 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TWPI. It covers every address from 58:21:E9:00:00:00 to 58:21:E9:FF:FF:FF, or 16,777,216 addresses in total. It is also written 58-21-E9.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 58:21:E9:00:00:00 that is 58:21:E9 — 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 TWPI located?

TWPI is listed at PMB# 335; 1121 Annapolis Road Odenton MD US 21113 in the IEEE OUI registry entry for 58:21:E9. This is the address the organization registered with the IEEE, which may differ from its current operating address.

TWPI

MAC address prefix 58:21:E9 is registered to TWPI in the IEEE OUI registry. Any device whose MAC address begins with 58:21:E9 has a network interface built by TWPI. 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 58:21:E9:00:00:00 to 58:21:E9:FF:FF:FF.

OUI prefix: 58:21:E9
Hyphen form: 58-21-E9
MAC range: 58:21:E9:00:00:00 – 58:21:E9:FF:FF:FF
Addresses in block: 16,777,216
Organization: TWPI
Address: PMB# 335; 1121 Annapolis Road Odenton MD US 21113
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.

2018-12-21Assigned to "TWPI"
archived source →
2026-07-17Assigned to "TWPI"

Nearby in the registry

The prefixes assigned immediately before and after 58:21:E9:

FAQ

Which company owns MAC address prefix 58:21:E9?: MAC address prefix 58:21:E9 is registered to TWPI in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 58:21:E9 has a network interface built by TWPI.
What is the OUI 58:21:E9?: 58:21:E9 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TWPI. It covers every address from 58:21:E9:00:00:00 to 58:21:E9:FF:FF:FF, or 16,777,216 addresses in total. It is also written 58-21-E9.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 58:21:E9:00:00:00 that is 58:21:E9 — 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 TWPI located?: TWPI is listed at PMB# 335; 1121 Annapolis Road Odenton MD US 21113 in the IEEE OUI registry entry for 58:21:E9. This is the address the organization registered with the IEEE, which may differ from its current operating address.