Which company owns MAC address prefix E0:31:5D?

MAC address prefix E0:31:5D is registered to EM Microelectronic in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with E0:31:5D has a network interface built by EM Microelectronic.

What is the OUI E0:31:5D?

E0:31:5D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to EM Microelectronic. It covers every address from E0:31:5D:00:00:00 to E0:31:5D:FF:FF:FF, or 16,777,216 addresses in total. It is also written E0-31-5D.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in E0:31:5D:00:00:00 that is E0:31:5D — 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 EM Microelectronic located?

EM Microelectronic is listed at Rue des Sors 3 Marin-Epagnier Neuchatel CH 2074 in the IEEE OUI registry entry for E0:31:5D. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does EM Microelectronic own?

EM Microelectronic holds 74 OUI prefixes in the IEEE registry, of which E0:31:5D is one. A device made by EM Microelectronic could carry a MAC address from any of them.

EM Microelectronic

MAC address prefix E0:31:5D is registered to EM Microelectronic in the IEEE OUI registry. Any device whose MAC address begins with E0:31:5D has a network interface built by EM Microelectronic. 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 E0:31:5D:00:00:00 to E0:31:5D:FF:FF:FF.

OUI prefix: E0:31:5D
Hyphen form: E0-31-5D
MAC range: E0:31:5D:00:00:00 – E0:31:5D:FF:FF:FF
Addresses in block: 16,777,216
Organization: EM Microelectronic
Address: Rue des Sors 3 Marin-Epagnier Neuchatel CH 2074
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.

Other prefixes from EM Microelectronic

EM Microelectronic holds 74 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2026-01-08Assigned to "EM Microelectronic"
archived source →
2026-07-17Assigned to "EM Microelectronic"

Nearby in the registry

The prefixes assigned immediately before and after E0:31:5D:

FAQ

Which company owns MAC address prefix E0:31:5D?: MAC address prefix E0:31:5D is registered to EM Microelectronic in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with E0:31:5D has a network interface built by EM Microelectronic.
What is the OUI E0:31:5D?: E0:31:5D is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to EM Microelectronic. It covers every address from E0:31:5D:00:00:00 to E0:31:5D:FF:FF:FF, or 16,777,216 addresses in total. It is also written E0-31-5D.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in E0:31:5D:00:00:00 that is E0:31:5D — 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 EM Microelectronic located?: EM Microelectronic is listed at Rue des Sors 3 Marin-Epagnier Neuchatel CH 2074 in the IEEE OUI registry entry for E0:31:5D. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does EM Microelectronic own?: EM Microelectronic holds 74 OUI prefixes in the IEEE registry, of which E0:31:5D is one. A device made by EM Microelectronic could carry a MAC address from any of them.