Cisco Cisco Customer Voice Portal Downloads

that until it stops
responding.

If the Gatekeeper has
alternate endpoints

Call is sent to Unified
CallManager and IP

Agent transfer instructions from H.323 Service to agent destination

configured for the agent

phone specified by the
Gatekeeper.

destination, then the
H.323 Service will try
each endpoint in
succession. If no target
can accept the transfer,
H.323 Service sends a
connect failure message
back to IVR Service,
which sends a failure back
to Unified ICME.

Survivability of Existing Calls

The sections above touch on high availability with respect to handling of new incoming calls
in the face of failed components. In this section we discuss the handling of existing calls when
components fail.

Call is lost. [SIP or H.323]

Ingress Gateway

If single Proxy Server, call will be lost. But if proxy pair is
deployed, further SIP messaging will simply go through the

SIP Proxy Server

other Proxy Server in the pair. Even if failure occurs during
an Invite transaction, the Ingress Gateway will time-out
waiting for a response and continue the transaction with the
other Proxy Server in the pair.

Media path remains connected to the VXML Gateway or
to the agent, but signaling through the SIP and IVR Services

Call Server (SIP Service)

is lost. If connected to the VXML Gateway, the IOS Voice
Browser will time-out, but will not be able to inform the
Ingress Gateway of the failure. The Ingress Gateway will
time-out either its SIP session timer or its RTP media
inactivity timer and invoke the Survivability script.

If connected to an agent, the parties can continue talking
for some time. The RTP media inactivity timer will not
expire, but the SIP session timer will time-out and try to
"refresh" the session. This involves a new Invite transaction,
which, if the Call Server came back up in the meantime,

Planning Guide for Cisco Unified Customer Voice Portal 4.0(1)