The MAC address of a handset acts as a unique identifier, and is required when adding handsets to the automatic provisioning system.
The MAC address can be found in the following locations:
On the box your handset was shipped in, locate the label on the side. This will include the phone's MAC address and a scannable barcode.
You can locate the MAC address, along with the scannable barcode, on the rear of your device, normally near the bottom, as the image below shows.
If the phone's already powered on and connected to network, you can retrieve the MAC from the phone's web interface. To do so, tap the OK button briefly, then enter the IPv4 address into your web browser. To retrieve the IP address of a cordless handset, see Yealink W60 / W52 / W56 Cordless Phones - How to get the Base IP address
At the login prompt, enter the credentials (by default, this is username: admin and password: admin).
On the status page, look for the MAC address in the Network section.