Polycom RMX 1500 Administrator's Manual page 849

Disconnection Causes
IP Disconnection Causes.
If a participant was unable to connect to a conference or was disconnected
from a conference, the Connection Status tab in the Participant Properties
dialog box indicates the call disconnection cause. In some cases, a possible
solution may be displayed.
A video participant who is unable to connect the video channels, but is
able to connect as an audio only participant, is referred to as a Secondary
participant. For Secondary participants, the Connection Status tab in the
Participant Properties dialog box indicates the video disconnection cause.
In some cases, a possible solution may be indicated.
The table below lists the call disconnection causes that can be displayed in
the Call Disconnection Cause field and provides an explanation of each
message
Table A-1 Call Disconnection Causes
Disconnection Cause
Disconnected by User
Remote device did not
open the encryption
signaling channel
Remote devices selected
encryption algorithm does
not match the local
selected encryption
algorithm
Appendix A
Description
The user disconnected the endpoint from the
conference.
The endpoint did not open the encryption
signaling channel.
The encryption algorithm selected by the
endpoint does not match the MCU's encryption
algorithm.
A-1