Presence Services (i.e. the Presence Server
and the Presence User Agent) are both
disabled by default.
These services can be enabled and disabled
separately from each other, depending on the
nature of your deployment.

PUA

Enabled

If the PUA is enabled, it will publish presence
information for all locally registered endpoints,
whether or not those endpoints are also
publishing their own presence information.
Information published by the PUA will be routed
to a Presence Server acting for the endpoint’s
domain. This could be the local Presence
Server, or (if this is disabled) a Presence
Server on another system that is authoritative
for that domain.

Disabled

If the PUA is disabled, only those endpoints
that support presence will publish presence
information. No information will be available
for endpoints that do not support presence.

Presence Server

Regardless of whether or not the Presence
Server is enabled, the VCS will still continue to
receive PUBLISH messages if they are sent to
it from any of the following sources:

locally registered endpoints that support

•

presence

the local PUA (if enabled)

•

remote SIP Proxies

•

Enabled

If the local Presence Server is enabled, it will
process any PUBLISH messages intended for
the SIP domains for which the local VCS is
authoritative. All other PUBLISH messages will
be proxied on in accordance with the VCS’s SIP
routing rules.

Disabled

If the local Presence Server is disabled, the
VCS will proxy on all PUBLISH messages to one
or more of its neighbor zones in accordance
with its locally configured

call processing

rules. The local VCS will do this regardless
of whether or not it is authoritative for the
presentity’s domain. If one of these neighbors
is authoritative for the domain, and has a
Presence Server enabled, then that neighbor
will provide presence information for the
presentity.

Status

This section shows whether
the Presence Server and
Presence User Agent are
active or inactive.

For information about how Presence works within a VCS cluster, see the

Clustering and

Presence

section.

The recommended configuration for a
VCS Expressway when acting as a
traversal server for a VCS Control is to

enable the PUA and disable the Presence
Server on the VCS Expressway, and enable
the Presence Server on the VCS Control. This
will ensure that all PUBLISH messages
generated by the PUA are routed to the VCS
Control.

We recommend that if you have a
deployment with two or more VCSs
neighbored together, you enable the

presence server on just one VCS. This will
ensure a central source of information for all
presentities in your network.