Which company owns MAC address prefix 78:3D:5B?

MAC address prefix 78:3D:5B is registered to TELNET Redes Inteligentes S.A. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 78:3D:5B has a network interface built by TELNET Redes Inteligentes S.A..

What is the OUI 78:3D:5B?

78:3D:5B is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TELNET Redes Inteligentes S.A.. It covers every address from 78:3D:5B:00:00:00 to 78:3D:5B:FF:FF:FF, or 16,777,216 addresses in total. It is also written 78-3D-5B.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 78:3D:5B:00:00:00 that is 78:3D:5B — 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 TELNET Redes Inteligentes S.A. located?

TELNET Redes Inteligentes S.A. is listed at Polígono Industrial Centrovía La Muela Zaragoza ES 50198 in the IEEE OUI registry entry for 78:3D:5B. This is the address the organization registered with the IEEE, which may differ from its current operating address.

TELNET Redes Inteligentes S.A.

MAC address prefix 78:3D:5B is registered to TELNET Redes Inteligentes S.A. in the IEEE OUI registry. Any device whose MAC address begins with 78:3D:5B has a network interface built by TELNET Redes Inteligentes S.A.. 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 78:3D:5B:00:00:00 to 78:3D:5B:FF:FF:FF.

OUI prefix: 78:3D:5B
Hyphen form: 78-3D-5B
MAC range: 78:3D:5B:00:00:00 – 78:3D:5B:FF:FF:FF
Addresses in block: 16,777,216
Organization: TELNET Redes Inteligentes S.A.
Address: Polígono Industrial Centrovía La Muela Zaragoza ES 50198
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 "TELNET Redes Inteligentes S.A."
archived source →
2026-07-17Assigned to "TELNET Redes Inteligentes S.A."

Nearby in the registry

The prefixes assigned immediately before and after 78:3D:5B:

FAQ

Which company owns MAC address prefix 78:3D:5B?: MAC address prefix 78:3D:5B is registered to TELNET Redes Inteligentes S.A. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 78:3D:5B has a network interface built by TELNET Redes Inteligentes S.A..
What is the OUI 78:3D:5B?: 78:3D:5B is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to TELNET Redes Inteligentes S.A.. It covers every address from 78:3D:5B:00:00:00 to 78:3D:5B:FF:FF:FF, or 16,777,216 addresses in total. It is also written 78-3D-5B.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 78:3D:5B:00:00:00 that is 78:3D:5B — 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 TELNET Redes Inteligentes S.A. located?: TELNET Redes Inteligentes S.A. is listed at Polígono Industrial Centrovía La Muela Zaragoza ES 50198 in the IEEE OUI registry entry for 78:3D:5B. This is the address the organization registered with the IEEE, which may differ from its current operating address.