Yealink SIP-T54S Administrator's Manual page 977

Parameter
If it is set to 0 (Disabled), the IP phone will not use voice encryption service.
If it is set to 1 (Optional), the IP phone will negotiate with the other IP phone what type of
encryption to utilize for the session.
If it is set to 2 (Compulsory), the IP phone is forced to use SRTP during a call.
X ranges from 1 to 16 (for SIP-T54S/T48G/T48S/T46G/T46S/T29G)
X ranges from 1 to 12 (for SIP-T52S/T42G/T42S)
X ranges from 1 to 6 (for SIP-T41P/T41S/T27P/T27G)
X ranges from 1 to 3 (for SIP-T40P/T40G/T23P/T23G)
X ranges from 1 to 2 (for SIP-T21(P) E2)
X is equal to 1 (for SIP-T19(P) E2/CP860/CP920)
Web User Interface:
Account->Advanced->RTP Encryption(SRTP)
Phone User Interface:
None
To configure SRTP feature via web user interface:
Click on Account->Advanced.
1.
Select the desired account from the pull-down list of Account.
2.
Select the desired value from the pull-down list of RTP Encryption(SRTP).
3.
Click Confirm to accept the change.
4.
Configuring Security Features
Permitted Values Default
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