Which company owns MAC address prefix B4:A5:EF?

MAC address prefix B4:A5:EF is registered to Sercomm Corporation. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with B4:A5:EF has a network interface built by Sercomm Corporation..

What is the OUI B4:A5:EF?

B4:A5:EF is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Sercomm Corporation.. It covers every address from B4:A5:EF:00:00:00 to B4:A5:EF:FF:FF:FF, or 16,777,216 addresses in total. It is also written B4-A5-EF.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in B4:A5:EF:00:00:00 that is B4:A5:EF — 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 Sercomm Corporation. located?

Sercomm Corporation. is listed at 3F,No.81,Yu-Yih Rd.,Chu-Nan Chen Miao-Lih Hsuan TW 115 in the IEEE OUI registry entry for B4:A5:EF. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Sercomm Corporation. own?

Sercomm Corporation. holds 19 OUI prefixes in the IEEE registry, of which B4:A5:EF is one. A device made by Sercomm Corporation. could carry a MAC address from any of them.

Sercomm Corporation.

MAC address prefix B4:A5:EF is registered to Sercomm Corporation. in the IEEE OUI registry. Any device whose MAC address begins with B4:A5:EF has a network interface built by Sercomm Corporation.. 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 B4:A5:EF:00:00:00 to B4:A5:EF:FF:FF:FF.

OUI prefix: B4:A5:EF
Hyphen form: B4-A5-EF
MAC range: B4:A5:EF:00:00:00 – B4:A5:EF:FF:FF:FF
Addresses in block: 16,777,216
Organization: Sercomm Corporation.
Address: 3F,No.81,Yu-Yih Rd.,Chu-Nan Chen Miao-Lih Hsuan TW 115
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 Sercomm Corporation.

Sercomm Corporation. holds 19 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.

2016-07-29Assigned to "Sercomm Corporation."
archived source →
2026-07-17Assigned to "Sercomm Corporation."

Nearby in the registry

The prefixes assigned immediately before and after B4:A5:EF:

FAQ

Which company owns MAC address prefix B4:A5:EF?: MAC address prefix B4:A5:EF is registered to Sercomm Corporation. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with B4:A5:EF has a network interface built by Sercomm Corporation..
What is the OUI B4:A5:EF?: B4:A5:EF is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Sercomm Corporation.. It covers every address from B4:A5:EF:00:00:00 to B4:A5:EF:FF:FF:FF, or 16,777,216 addresses in total. It is also written B4-A5-EF.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in B4:A5:EF:00:00:00 that is B4:A5:EF — 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 Sercomm Corporation. located?: Sercomm Corporation. is listed at 3F,No.81,Yu-Yih Rd.,Chu-Nan Chen Miao-Lih Hsuan TW 115 in the IEEE OUI registry entry for B4:A5:EF. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Sercomm Corporation. own?: Sercomm Corporation. holds 19 OUI prefixes in the IEEE registry, of which B4:A5:EF is one. A device made by Sercomm Corporation. could carry a MAC address from any of them.