The PG is the
component that talks to the telephony devices through their own proprietary CTI
interface in a Unified CCE system. These devices can be ACDs, IVR devices or,
in cases such as with the Unified CCE, an IP PBX. The PG normalizes whatever
protocol the telephony device speaks, and keeps track of the state of agents
and calls that are on that device. The PG sends this status to the Router, as
well as forwards requests requiring customer logic to the Router.
The PG also exposes
a normalized CTI interface to clients. These clients can be traditional CTI
clients (wallboards, agent/supervisor desktop clients, and so on), or they can
be another instance of Unified CCE, as is the case in a parent/child
The component of the
PG that does the normalization is called a Peripheral Interface Manager (PIM).
This component talks to the peripheral and translates whatever proprietary
language it speaks into the normalized one that the Open Peripheral Controller
(OPC) and the rest of the PG understand.
PGs fall into
several groups. The first classification of PG includes those that talk to an
ACD or Unified CM that has agents on it. This is the typical case for a PG. It
talks a proprietary CTI protocol to the switch, and maintains the state of
agents and calls in queue on the device. While all of these PGs report agent
state to the Central Controller, they do it in a different way. In the case of
a PG talking to an ACD, the PG mirrors the state of the agents on the ACD; it
keeps a copy of the master state of the agents tracked by the ACD. In the case
of a PG attached to a Unified CM, the Unified CM does not know about agents or
agent states, it only knows about phone lines. In this case the PG is the
master for the agent state.
classification of PG is a VRU or Media Routing (MR) PG. These PGs expose an
interface that is client-neutral. In the case of the VRU PG, this interface is
tailored to voice calls; in the case of the MR PG, it is more generic task
routing that is exposed. These PGs do not maintain agent state, but only
maintain the state of calls (or tasks) and expose an interface for the devices
to get instructions from the Router.
classification of PG is the group PG. There are two types of PGs that talk to
groups of peripherals. The first is the Generic PG. This PG allows multiple
PIMs of different types to reside inside of the same PG. Each peripheral on
this PG behaves completely independently. Currently the Generic PG is supported
only for the Unified CCE, where it contains a Communications Manager PIM and a
VRU PIM talking to an IP-IVR or Customer Voice Portal (CVP). The second type of
group PG is a Unified CCE System PG. This PG, like the generic PG, has one Call
Manager PIM and one or more VRU PIMs. The System PG ties these multiple PIMs
together. In a traditional Unified CCE, a call that comes into the
Communications Manager then gets transferred to the IP-IVR and then back to an
agent looks like three separate calls to the Unified CCE. The System PG
coordinates these calls and makes that call look like a single call. This is
what happens on a traditional TDM ACD, where the ACD also has a queue point.
Figure 3. Peripheral
The PG is duplexed
using the same technology as the Central Controller, MDS. This means that there
are two PGs operating at any time. All of the messages to the critical process
on the PG (OPC) go through the MDS queue, to keep the two operating in
lock-step. However, the PG operates slightly different from the Router – from a
fault tolerance standpoint – in that while both sides share the same data, for
many PG components, only one side is active. Should a fault occur, the opposite
side activates and continues functioning, having the context of the other side
without losing calls.
PGs use the Device
Management Protocol (DMP) to communicate between themselves and the central
controller. The following figure depicts the components involved in this
communication and the communication links employed.
Figure 4. DMP
Coresident with the
PG is the CTI Gateway (CG - CTI Server component) and the Cisco Computer
Telephony Integration Option (CTI OS).