Yealink W60P Administrator's Manual page 433

Click Browse to select the certificate (*.pem, *.crt, *.cer or *.der) from your local system.
2.
Click Upload to upload the certificate.
3.
To configure the server certificates via web user interface:
Click on Security->Server Certificates.
1.
Select the desired value from the pull-down list of Device Certificates.
2.
Click Confirm to accept the change.
3.
To upload a server certificate via web user interface:
Click on Security->Server Certificates.
1.
Configuring Security Features
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