Which company owns MAC address prefix 00:A0:03?

MAC address prefix 00:A0:03 is registered to Siemens Switzerland Ltd., I B T HVP in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:A0:03 has a network interface built by Siemens Switzerland Ltd., I B T HVP.

What is the OUI 00:A0:03?

00:A0:03 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Siemens Switzerland Ltd., I B T HVP. It covers every address from 00:A0:03:00:00:00 to 00:A0:03:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-A0-03.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 00:A0:03:00:00:00 that is 00:A0:03 — 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 Siemens Switzerland Ltd., I B T HVP located?

Siemens Switzerland Ltd., I B T HVP is listed at Building Technologies Division, International Headquarters Zug CH 6301 in the IEEE OUI registry entry for 00:A0:03. This is the address the organization registered with the IEEE, which may differ from its current operating address.

Siemens Switzerland Ltd., I B T HVP

MAC address prefix 00:A0:03 is registered to Siemens Switzerland Ltd., I B T HVP in the IEEE OUI registry. Any device whose MAC address begins with 00:A0:03 has a network interface built by Siemens Switzerland Ltd., I B T HVP. 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 00:A0:03:00:00:00 to 00:A0:03:FF:FF:FF.

OUI prefix: 00:A0:03
Hyphen form: 00-A0-03
MAC range: 00:A0:03:00:00:00 – 00:A0:03:FF:FF:FF
Addresses in block: 16,777,216
Organization: Siemens Switzerland Ltd., I B T HVP
Address: Building Technologies Division, International Headquarters Zug CH 6301
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 "Siemens Switzerland Ltd., I B T HVP"
archived source →
2026-07-17Assigned to "Siemens Switzerland Ltd., I B T HVP"

Nearby in the registry

The prefixes assigned immediately before and after 00:A0:03:

FAQ

Which company owns MAC address prefix 00:A0:03?: MAC address prefix 00:A0:03 is registered to Siemens Switzerland Ltd., I B T HVP in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:A0:03 has a network interface built by Siemens Switzerland Ltd., I B T HVP.
What is the OUI 00:A0:03?: 00:A0:03 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Siemens Switzerland Ltd., I B T HVP. It covers every address from 00:A0:03:00:00:00 to 00:A0:03:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-A0-03.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 00:A0:03:00:00:00 that is 00:A0:03 — 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 Siemens Switzerland Ltd., I B T HVP located?: Siemens Switzerland Ltd., I B T HVP is listed at Building Technologies Division, International Headquarters Zug CH 6301 in the IEEE OUI registry entry for 00:A0:03. This is the address the organization registered with the IEEE, which may differ from its current operating address.