Polycom RealPresence 800s Administrator's Manual page 653

RealPresence Collaboration Server (RMX) 800s/Virtual Edition Administrator's Guide
Disconnection Cause
SIP server error 505
SIP temporarily not available
SIP remote device did not respond in the
given time frame
SIP trans error TCP Invite
SIP transport error
SIP unauthorized
SIP unsupported media type
Polycom®, Inc.
Description
The SIP server sent a SIP Server Error 505 (Version Not Supported)
response.
The server does not support, or refuses to support, the SIP protocol
version that was used in the request.
The participant's endpoint was contacted successfully but the
participant is currently unavailable (e.g., not logged in or logged in such
a manner as to preclude communication with the participant).
The endpoint did not respond in the given time frame.
A SIP Invite was sent via TCP, but the endpoint was not found.
Unable to initiate connection with the endpoint.
The request requires user authentication.
The server is refusing to service the request because the message
body of the request is in a format not supported by the requested
resource for the requested method.
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