Polycom RMX 1500 Administrator's Manual page 137

Chapter 2-Additional Conferencing Information
The participant encryption status is also indicated in the Participant
Properties – SDP tab, where SRTP indication is listed for each encrypted
channel (for example, audio and video).
An encrypted participant who is unable to join a conference is
disconnected from the conference. The disconnection cause is displayed
in the Participant Properties – Connection Status tab, Security Failure
indication, and the Cause box identifies the encryption related situation.
For more information about monitoring, see "Conference and Participant
Monitoring" on page 11-1.
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