Which company owns MAC address prefix 18:C4:51?

MAC address prefix 18:C4:51 is registered to Tucson Embedded Systems in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 18:C4:51 has a network interface built by Tucson Embedded Systems.

What is the OUI 18:C4:51?

18:C4:51 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Tucson Embedded Systems. It covers every address from 18:C4:51:00:00:00 to 18:C4:51:FF:FF:FF, or 16,777,216 addresses in total. It is also written 18-C4-51.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 18:C4:51:00:00:00 that is 18:C4:51 — 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 Tucson Embedded Systems located?

Tucson Embedded Systems is listed at 5620 North Kolb Road Tucson AZ US 85750 in the IEEE OUI registry entry for 18:C4:51. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Tucson Embedded Systems

MAC address prefix 18:C4:51 is registered to Tucson Embedded Systems in the IEEE OUI registry. Any device whose MAC address begins with 18:C4:51 has a network interface built by Tucson Embedded Systems. 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 18:C4:51:00:00:00 to 18:C4:51:FF:FF:FF.

OUI prefix: 18:C4:51
Hyphen form: 18-C4-51
MAC range: 18:C4:51:00:00:00 – 18:C4:51:FF:FF:FF
Addresses in block: 16,777,216
Organization: Tucson Embedded Systems
Address: 5620 North Kolb Road Tucson AZ US 85750
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 "Tucson Embedded Systems"
archived source →
2026-07-17Assigned to "Tucson Embedded Systems"

Nearby in the registry

The prefixes assigned immediately before and after 18:C4:51:

FAQ

Which company owns MAC address prefix 18:C4:51?: MAC address prefix 18:C4:51 is registered to Tucson Embedded Systems in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 18:C4:51 has a network interface built by Tucson Embedded Systems.
What is the OUI 18:C4:51?: 18:C4:51 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Tucson Embedded Systems. It covers every address from 18:C4:51:00:00:00 to 18:C4:51:FF:FF:FF, or 16,777,216 addresses in total. It is also written 18-C4-51.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 18:C4:51:00:00:00 that is 18:C4:51 — 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 Tucson Embedded Systems located?: Tucson Embedded Systems is listed at 5620 North Kolb Road Tucson AZ US 85750 in the IEEE OUI registry entry for 18:C4:51. This is the address the organization registered with the IEEE, which may differ from its current operating address.