Cisco Cisco Expressway Maintenance Manual
To support ENUM dialing on the Expressway you must configure it with at least one DNS server and the appropriate
ENUM zones.
ENUM zones.
Full instructions on how to configure the Expressway to support ENUM dialing (both outbound and inbound) are given
in the
in the
Dialing by IP Address
Dialing by IP address is necessary when the destination endpoint is not registered with any system.
Calls to unknown IP addresses
Although the Expressway supports dialing by IP address, it is sometimes undesirable for the Expressway to be allowed
to place a call directly to an IP address that is not local. Instead, you may want a neighbor to place the call on behalf
of the Expressway, or not allow such calls at all. The Calls to unknown IP addresses setting (on the
to place a call directly to an IP address that is not local. Instead, you may want a neighbor to place the call on behalf
of the Expressway, or not allow such calls at all. The Calls to unknown IP addresses setting (on the
network, or registered with one of its neighbors:
■
Direct: the Expressway attempts to place the call directly to the unknown IP address without querying any
neighbors.
neighbors.
■
Indirect: the Expressway forwards the search request to its neighbors in accordance with its normal search
process, meaning any zones that are the target of search rules with an Any IP Address mode. If a match is
found and the neighbor’s configuration allows it to connect a call to that IP address, the Expressway will pass
the call to that neighbor for completion.
process, meaning any zones that are the target of search rules with an Any IP Address mode. If a match is
found and the neighbor’s configuration allows it to connect a call to that IP address, the Expressway will pass
the call to that neighbor for completion.
■
Off: the Expressway will not attempt to place the call, either directly or indirectly to any of its neighbors.
The default setting is Indirect.
This setting applies to the call's destination address prior to any zone transforms, but after any pre-search transforms
or Call Policy rules have been applied.
or Call Policy rules have been applied.
Calling unregistered endpoints
An unregistered endpoint is any device that is not registered with an H.323 gatekeeper or SIP registrar. Although most
calls are made between endpoints that are registered with such systems, it is sometimes necessary to place a call to
an unregistered endpoint.
calls are made between endpoints that are registered with such systems, it is sometimes necessary to place a call to
an unregistered endpoint.
There are two ways to call to an unregistered endpoint:
■
by dialing its URI (this requires that the local Expressway is configured to support URI dialing, and a DNS record
exists for that URI that resolves to the unregistered endpoint's IP address)
exists for that URI that resolves to the unregistered endpoint's IP address)
■
by dialing its IP address
Recommended configuration for firewall traversal
When an Expressway-E is neighbored with an Expressway-C for firewall traversal, you should typically set Calls to
unknown IP addresses to Indirect on the Expressway-C and Direct on the Expressway-E.
unknown IP addresses to Indirect on the Expressway-C and Direct on the Expressway-E.
About ENUM Dialing
ENUM dialing allows an endpoint to be contacted by a caller dialing an E.164 number - a telephone number - even if
that endpoint has registered using a different format of alias.
that endpoint has registered using a different format of alias.
Using ENUM dialing, when an E.164 number is dialed it is converted into a URI using information stored in DNS. The
Expressway then attempts to find the endpoint based on the URI that has been returned.
Expressway then attempts to find the endpoint based on the URI that has been returned.
The ENUM dialing facility allows you to retain the flexibility of URI dialing while having the simplicity of being called
using just a number - particularly important if any of your callers are restricted to dialing using a numeric keypad.
using just a number - particularly important if any of your callers are restricted to dialing using a numeric keypad.
The Expressway supports outward ENUM dialing by allowing you to configure ENUM zones on the Expressway. When
an ENUM zone is queried, this triggers the Expressway to transform the E.164 number that was dialed into an ENUM
domain which is then queried for using DNS.
an ENUM zone is queried, this triggers the Expressway to transform the E.164 number that was dialed into an ENUM
domain which is then queried for using DNS.
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Cisco Expressway Administrator Guide