Yealink SIP-T20 - Manual (Page 113)

Troubleshooting
101
How to make a call using SRTP?
You can enable SRTP to encrypt the audio stream(s) of phone calls. The parties
participating in the call should enable SRTP. You can enable SRTP on a per-line basis.
To enable SRTP via web user interface:
1. Click on Account.
2. Select the desired account from the pull-down list of Account.
3. Click on Advanced.
4. Select the desired value from the pull-down list of RTP Encryption (SRTP).
5. Click Confirm to accept the change.
Note
How to reboot the phone?
To reboot the phone via web user interface:
1. Click on Settings->Upgrade.
SRTP is not available on all servers. Contact your system administrator for more
information.
SRTP is configurable via web user interface only.