Chapter 5-Cascading Conferences
Polycom, Inc. 5-5
Once the DTMF codes are entered and forwarded to the Entry Queue on MCU B, the IVR
session is completed, the participant moved to the destination conference and the
connection between the two conferences is established.

Automatic Identification of the Cascading Link

In both dialing methods, the system automatically identifies that the dial in participant is an
MCU and creates a Cascading Link and displays the link icon for the participant ( ). The
master-slave relationship is randomly defined by the MCUs during the negotiation process
of the connection phase.

Suppression of DTMF Forwarding

Forwarding of the DTMF codes from one conference to another over an ISDN cascading link
is not automatically suppressed as with IP cascading link and it can be limited to basic
operations while suppressing all other operations by a system flag:
DTMF_FORWARD_ANY_DIGIT_TIMER_SECONDS.
System Flag Settings
The DTMF_FORWARD_ANY_DIGIT_TIMER_SECONDS flag determines the time
period (in seconds) that MCU A will forward DTMF inputs from conference A participants
to MCU B.
Once the timer expires, most of the DTMF codes (excluding five operations as for IP links)
entered in conference A will not be forwarded to conferenceB. This is done to prevent an
operation requested by a participant individually (for example, mute my line) to be applied
to all the participants in conference B.
Flag range (in seconds): 0 - 360000
This flag is defined on MCU A (the calling MCU).
If a flag is not listed in the System Flags list it must be added to the system.cfg file before it can
be modified. For more details on defining system flags, see "Modifying System Flags” on
page20-1.
Star Cascading Topology
In the Star topology (as well as in the Basic topology), the MCUs are usually installed at
different locations (states/countries) and participants connect to their local MCU to facilitate
the connection and save long distance call costs. Star Topology Cascading requires that all
cascaded MCUs reside on the same network.
Content sharing is available to all conferences over the H.323 Cascading Link.
In this topology, the MCUs are networked together using two modes:
• Master-Slave Cascading
• Cascading via Entry Queue
Although participants in Star Cascading conferences can connect to their local conference using
H.323, SIP and ISDN, the Cascading Links between conferences must connect via H.323.