Cisco Cisco Expressway Maintenance Manual
Field
Description
Usage tips
Calls to
unknown IP
addresses
unknown IP
addresses
Determines the way in which the Expressway attempts to call
systems which are not registered with it or one of its
neighbors.
systems which are not registered with it or one of its
neighbors.
Direct: allows an endpoint to make a call to an unknown IP
address without the Expressway querying any neighbors. The
call setup would occur just as it would if the far end were
registered directly to the local system.
address without the Expressway querying any neighbors. The
call setup would occur just as it would if the far end were
registered directly to the local system.
Indirect: upon receiving a call to an unknown IP address, the
Expressway will query its neighbors for the remote address
and if permitted will route the call through the neighbor.
Expressway will query its neighbors for the remote address
and if permitted will route the call through the neighbor.
Off: endpoints registered directly to the Expressway may only
call an IP address of a system also registered directly to that
Expressway.
call an IP address of a system also registered directly to that
Expressway.
The default is Indirect.
This setting applies to the call's
destination address prior to any
zone transforms, but after any
pre-search transforms, Call
Policy or User Policy rules have
been applied.
destination address prior to any
zone transforms, but after any
pre-search transforms, Call
Policy or User Policy rules have
been applied.
In addition to controlling calls,
this setting also determines the
behavior of provisioning
messages to SIP devices, as
these messages are routed to IP
addresses.
this setting also determines the
behavior of provisioning
messages to SIP devices, as
these messages are routed to IP
addresses.
Fallback alias
The alias to which incoming calls are placed for calls where
the IP address or domain name of the Expressway has been
given but no callee alias has been specified.
the IP address or domain name of the Expressway has been
given but no callee alias has been specified.
If no fallback alias is configured,
calls that do not specify an alias
will be disconnected. See below
for more information.
calls that do not specify an alias
will be disconnected. See below
for more information.
About the Fallback Alias
The Expressway could receive a call that is destined for it but which does not specify an alias. This could be for one
of the following reasons:
of the following reasons:
■
the caller has dialed the IP address of the Expressway directly
■
the caller has dialed a domain name belonging to the Expressway (either one of its configured SIP domains, or
any domain that has an SRV record that points at the IP address of the Expressway), without giving an alias as
a prefix
any domain that has an SRV record that points at the IP address of the Expressway), without giving an alias as
a prefix
Normally such calls would be disconnected. However, such calls will be routed to the Fallback alias if it is specified.
Note that some endpoints do not allow users to enter an alias and an IP address to which the call should be placed.
Note that some endpoints do not allow users to enter an alias and an IP address to which the call should be placed.
Example usage
You may want to configure your fallback alias to be that of your receptionist, so that all calls that do not specify an
alias are still answered personally and can then be redirected appropriately.
alias are still answered personally and can then be redirected appropriately.
For example, Example Inc has the domain of
example.com
. The endpoint at reception has the alias
reception@example.com
. They configure their Expressway with a fallback alias of
reception@example.com
. This means
that any calls made directly to
example.com
(that is, without being prefixed by an alias), are forwarded to
reception@example.com
, where the receptionist can answer the call and direct it appropriately.
About Transforms and Search Rules
The Expressway can be configured to use transforms and search rules as a part of its call routing process.
Transforms
Transforms are used to modify the alias in a search request if it matches certain criteria. You can transform an alias
by removing or replacing its prefix, suffix, or the entire string, and by the use of regular expressions.
by removing or replacing its prefix, suffix, or the entire string, and by the use of regular expressions.
This transformation can be applied to the alias at two points in the routing process: as a pre-search transform, and as
a zone transform.
a zone transform.
168
Cisco Expressway Administrator Guide
Dial Plan and Call Processing