Which company owns MAC address prefix A4:E9:91?

MAC address prefix A4:E9:91 is registered to SISTEMAS AUDIOVISUALES ITELSIS S.L. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:E9:91 has a network interface built by SISTEMAS AUDIOVISUALES ITELSIS S.L..

What is the OUI A4:E9:91?

A4:E9:91 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to SISTEMAS AUDIOVISUALES ITELSIS S.L.. It covers every address from A4:E9:91:00:00:00 to A4:E9:91:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-E9-91.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in A4:E9:91:00:00:00 that is A4:E9:91 — 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 SISTEMAS AUDIOVISUALES ITELSIS S.L. located?

SISTEMAS AUDIOVISUALES ITELSIS S.L. is listed at POL.IND. DEL TAMBRE SANTIAGO COMPOSTELA A CORUÑA ES 15890 in the IEEE OUI registry entry for A4:E9:91. This is the address the organization registered with the IEEE, which may differ from its current operating address.

SISTEMAS AUDIOVISUALES ITELSIS S.L.

MAC address prefix A4:E9:91 is registered to SISTEMAS AUDIOVISUALES ITELSIS S.L. in the IEEE OUI registry. Any device whose MAC address begins with A4:E9:91 has a network interface built by SISTEMAS AUDIOVISUALES ITELSIS S.L.. 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:E9:91:00:00:00 to A4:E9:91:FF:FF:FF.

OUI prefix: A4:E9:91
Hyphen form: A4-E9-91
MAC range: A4:E9:91:00:00:00 – A4:E9:91:FF:FF:FF
Addresses in block: 16,777,216
Organization: SISTEMAS AUDIOVISUALES ITELSIS S.L.
Address: POL.IND. DEL TAMBRE SANTIAGO COMPOSTELA A CORUÑA ES 15890
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 "SISTEMAS AUDIOVISUALES ITELSIS S.L."
archived source →
2026-07-17Assigned to "SISTEMAS AUDIOVISUALES ITELSIS S.L."

Nearby in the registry

The prefixes assigned immediately before and after A4:E9:91:

FAQ

Which company owns MAC address prefix A4:E9:91?: MAC address prefix A4:E9:91 is registered to SISTEMAS AUDIOVISUALES ITELSIS S.L. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with A4:E9:91 has a network interface built by SISTEMAS AUDIOVISUALES ITELSIS S.L..
What is the OUI A4:E9:91?: A4:E9:91 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to SISTEMAS AUDIOVISUALES ITELSIS S.L.. It covers every address from A4:E9:91:00:00:00 to A4:E9:91:FF:FF:FF, or 16,777,216 addresses in total. It is also written A4-E9-91.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in A4:E9:91:00:00:00 that is A4:E9:91 — 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 SISTEMAS AUDIOVISUALES ITELSIS S.L. located?: SISTEMAS AUDIOVISUALES ITELSIS S.L. is listed at POL.IND. DEL TAMBRE SANTIAGO COMPOSTELA A CORUÑA ES 15890 in the IEEE OUI registry entry for A4:E9:91. This is the address the organization registered with the IEEE, which may differ from its current operating address.