Cisco Unified Contact Center Enterprise Solution Reference ...

Chapter 2 Deployment Models
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IPT: Multi-Site with Centralized Call Processing
In multi-site environments with distributed voice gateways, Unified CVP can be used to leverage the
ingress voice gateways at the remote sites as part of the traditional Unified CCE system to provide call
treatment and queueing at the remote location, using the VoiceXML Browser built into the Cisco IOS
voice gateway locally. Using the distributed gateways with Unified CVP permits calls to queue locally
in the ingress voice gateway and rather than requiring the call to cross the VoIP WAN to a centralized
queue platform. Only call signaling (H.323 and VoiceXML) pass over the WAN to instruct the remote
site voice gateway how to treat, queue, and transfer the call to an agent. In these models, pre-routing to
the site might not be necessary because Unified ICM takes control of the call as soon as it arrives at the
site. Basic carrier percent allocation can be used to allocate calls to the sites and failover (rollover) trunks
used to address local failures as needed.
Advantages
Only limited systems management skills are needed for the remote sites because most servers,
equipment, and system configurations are managed from a centralized location.
The Unified ICM pre-routing option can be used to load-balance calls across sites, including sites
with local PSTN trunks in addition to toll-free PSTN trunks.
No WAN RTP traffic is required for calls arriving at each remote site that are handled by agents at
that remote site.
Unified CVP provides call treatment and queueing at the remote site using the VoiceXML Browser
in Cisco IOS on the voice gateway itself, thus eliminating the need to move the call over the VoIP
WAN to a central queue and treatment point.
Best Practices
The Unified IP IVR or Unified CVP, Cisco Unified CallManager, and PGs (for both Cisco Unified
CallManager and IVR/Unified CVP) are co-located. In this model, the only Unified CCE
communications that can be separated across a WAN are the following:
– Unified ICM Central Controller to Unified ICM PG
– Unified ICM PG to Unified CCE Agent Desktops
– Cisco Unified CallManager to voice gateways
– Cisco Unified CallManager to phones
– Unified CVP Call Control Server to remote voice gateway (call control)
If calls are not going to be restricted to the site where calls arrive, or if calls will be made between
sites, more RTP traffic will flow across the WAN. It is important to determine the maximum number
of calls that will flow between sites or locations. Cisco Unified CallManager locations-based call
admission control failure will result in a routed call being disconnected (rerouting within
Cisco Unified CallManager is not currently supported). Therefore, it is important to provision
adequate bandwidth to the remote sites, and appropriately designed QoS for the WAN is critical.
H.323 or MGCP signaling traffic between the voice gateways and the centralized Cisco Unified
CallManager servers will flow over the WAN. Proper QoS implementation on the WAN is critical,
and signaling delays must be within tolerances listed in the latest version of the Cisco Unified
Communications Solution Reference Network Design (SRND) guide, available at
http://www.cisco.com/go/srnd
Cisco Unified Contact Center Enterprise 7.x SRND
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