Cisco Unified Contact Center Enterprise Solution Reference ...

Chapter 2 Deployment Models
IVR: Treatment and Queuing
Transfers
OL-8669-05
IPT: Multi-Site with Distributed Call Processing
The Unified ICM Central Controller provides the capability to create a single enterprise-wide queue.
The Unified ICM Central Controller provides consolidated reporting for all sites.
Best Practices
The Cisco Unified CallManager PG and Cisco Unified CallManager cluster must be co-located. The
Unified CVP PG and Unified CVP servers must be co-located.
The communication link from the Unified ICM Central Controller to PG must be properly sized and
provisioned for bandwidth and QoS. Cisco provides a partner tool called the VRU Peripheral
Gateway to Unified ICM Central Controller Bandwidth Calculator to assist in calculating the VRU
PG-to-Unified ICM bandwidth requirement. This tool is available online at
http://www.cisco.com/partner/WWChannels/technologies/resources/Unified
CC_resources.html
If the communication link between the PG and the Unified ICM Central Controller is lost, then all
contact center routing for calls at that site is lost. Therefore, it is important that a fault-tolerant WAN
is implemented. Even when a fault-tolerant WAN is implemented, it is important to identify
contingency plans for call treatment and routing when communication is lost between the Unified
ICM Central Controller and PG.
Latency between Unified ICM Central Controllers and remote PGs cannot exceed 200 ms one way
(400 ms round-trip)
Unified CVP queues and treats calls on the remote gateways, eliminating the need to terminate the voice
bearer traffic at the central site. Unified CVP servers may be located at the central site or distributed to
remote sites. WAN bandwidth must still be provisioned for transfers and conferences that involve agents
at other locations.
Unlike Unified IP IVR, with Unified CVP the call legs are torn down and reconnected, avoiding
signaling hairpins. With Unified IP IVR, two separate call signaling control paths will remain intact
between the two clusters (producing logical hairpinning and reducing the number of intercluster trunks
by two).
Transfers within a site function just like a single-site transfer. Transfers between Cisco Unified
CallManager clusters use either the VoIP WAN or a PSTN service.
If the VoIP WAN is used, sufficient intercluster trunks must be configured. An alternative to using the
VoIP WAN for routing calls between sites is to use a PSTN transfer service. These services allow the
Unified CCE voice gateways to outpulse DTMF tones to instruct the PSTN to reroute (transfer) the call
to another voice gateway location. Another alternative is to have the Cisco Unified CallManager cluster
at Site 1 make an outbound call back to the PSTN. The PSTN would then route the call to Site 2, but the
call would use two voice gateway ports at Site 1 for the remainder of the call.
Unified CCE: Unified CCE System PG
The Unified CCE System PG is not a good fit for this model because it does not support Unified CVP
for queuing, and the IVR PIMs on the Unified CCE System PG would go unused.
Cisco Unified Contact Center Enterprise 7.x SRND
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