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Installation and Upgrade Guide for Cisco Unified Videoconferencing 3522 BRI Gateway and 3527 PRI Gateway Release 5.5
OL-14910-01
Chapter 1 Functionality
About Gateway Features
DTMF translation The gateway supports translation between in-band Dual Tone
Multi-Frequency (DTMF) signals (on the ISDN side) and out-of-band
H.245 messages (on the IP side). DTMF translation occurs for voice and
video calls.
Dual video The gateway supports H.239 standards-based dual video and TANDBERG
DuoVideo technology. Dual video streams enable a screen to carry video
images from one source while simultaneously displaying images from a
second source.
Conceal caller ID The gateway supports a conceal caller ID feature that instructs the
gatekeeper to conceal the identity of the calling endpoint on the IP or
ISDN network, whether the presentation restricted feature is enabled or
not.
H.323 fast start The gateway H.323 fast start feature enables endpoints to join a voice
conference in the gateway more quickly.
ISDN rollover
(available in
Cisco Unified
Videoconferencing 35
27 PRI Gateway only)
The gateway features ISDN rollover. In this feature, the gateway sends a
“busy out” channel request to the PSTN switch when the current PRI
connection is left with less than a predefined number of available B
channels. The PSTN switch “rolls over” to the next available gateway.
Network Specific
Facility (available in
Cisco Unified
Videoconferencing 35
27 PRI Gateway only)
The gateway provides support for Network Specific Facility Information
Elements (NSF IEs) which enable system administrators to specify to
service providers the equipment, service, or network through which they
want a call routed.
ISDN connection
failure
The gateway responds to ISDN connection failure events, by unregistering
from its gatekeeper. The gatekeeper is forced to send new IP-to-ISDN
calls through a different gateway, thus ensuring high call completion rates.
The gateway re-registers to the gatekeeper when the ISDN connection is
restored.
Downspeeding The gateway features downspeeding functionality. In the downspeeding
feature, the gateway attempts to reconnect a disconnected video call either
at a lower bandwidth or as a voice call. Downspeeding contributes to a
higher percentage of call completion on the network. The gateway
supports downspeeding at call setup and in mid-call.
Multiple trap server
support
The gateway supports up to three SNMP trap servers.
H.239 support The gateway supports the H.239 protocol in ISDN-to-IP calls and in
IP-to-ISDN calls.
Encryption support The gateway supports H.235-compliant AES 128 encryption for calls over
IP networks, and H.233 and H.234-compliant AES 128 encryption for
calls over ISDN networks.
H.243 Conference
Control support
The gateway supports the H.243 protocol in ISDN-to-IP calls and in
IP-to-ISDN calls. The gateway identifies the protocol version that an IP
endpoint uses and sends H.239 capabilities only to those endpoints
working with protocol version 4.0 or later.
Table 1-1 Gateway Feature Summary (continued)
Feature Description