Yealink SIP-T4X Administration Manual page 197

Administrator's Guide for SIP-T4X IP Phones
5) Click Upload to upload the certificates.
c) If you select PEAP-MSCHAPv2:
1) Enter the user name for authentication in the Identity field.
2) Enter the password for authentication in the MD5 Password field.
3) In the CA Certificates field, click Browse to locate the desired certificate
(*.pem,*.crt, *.cer or *.der) from your local system.
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