Unexpected MAC address behavior for Mobile Broadband Interfaces in Windows

​​​​​​Summary

In Windows, the Media Access Control address (MAC address) assigned to Mobile broadband (MBB) network interfaces is automatically generated by the networking stack and derived from the International Mobile Equipment Identity (IMEI) of the cellular modem.

This behavior may unexpectedly result in MAC addresses that appear to use an Organizationally Unique Identifier (OUI) unrelated to the actual hardware manufacturer. This unexpected behavior may affect device identification policies that rely on MAC address consistency or vendor-specific OUIs.

Notes about the MAC address

• The generated MAC address is not required for cellular network communication and is used solely within the Windows networking stack.

• The MAC address may be visible through tools such as ipconfig, netsh, or through public network APIs. This might potentially lead to confusion or misidentification of the hardware vendor.

• For USB-connected cellular modems, the Microsoft class driver assigns the MAC address. There is no supported mechanism to modify or override this address.

• For PCIe-connected cellular modems using a NetAdapterCx/MbbCx client driver, developers may optionally set the MAC address using the following APIs:​​​​​​​

  • NetAdapterSetPermanentLinkLayerAddress function (netadapter.h)

  • NetAdapterSetCurrentLinkLayerAddress function (netadapter.h)