Requirements

• Yealink Power Adapter: 5V 2A power supply (ensure it's the correct model for Yealink T46G)
• Internet Access: To download the latest firmware from Yealink
• Web Browser: To access the phone's web interface
  

Steps:

1. Disconnect and Power On: Unplug the phone from the network and power it on.
2. Factory Reset Without Internet: Perform a factory reset without connecting it to the network. Navigate to the advanced menu by entering the password "admin" using the phone's dial pad (23466644), select "Reset & Reboot," and choose "Reset to factory settings."
3. Enable Web Interface: After the reset, go to the advanced menu again, select "Networking," and enable "Webserver type" on port 80.
4. Reboot and Connect: Let the phone reboot and connect it to the network only after it has fully booted. Press the OK button twice to see the IP address.
5. Access Web Interface: Open a web browser and log in using the default username "admin" and password "23646" (or "admin").
6. Firmware Upgrade: Click the settings tab, then upgrade. Download the latest Yealink firmware from Yealink's support page and upload it. The phone will reboot with the new firmware.