Cisco Cisco Expressway Maintenance Manual
■
configure at least one ENUM zone, and
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configure at least one DNS Server
section.
Incoming calls
To enable endpoints in your enterprise to receive incoming calls from other endpoints via ENUM dialing, you must
configure a DNS NAPTR record mapping your endpoints’ E.164 numbers to their SIP/H.323 URIs. See the
configure a DNS NAPTR record mapping your endpoints’ E.164 numbers to their SIP/H.323 URIs. See the
Note:
if an ENUM zone and a DNS server have not been configured on the local Expressway, calls made using ENUM
dialing could still be placed if the local Expressway is neighbored with another Expressway that has been
appropriately configured for ENUM dialing. Any ENUM dialed calls will go via the neighbor. This configuration is useful
if you want all ENUM dialing from your enterprise to be configured on one particular system.
appropriately configured for ENUM dialing. Any ENUM dialed calls will go via the neighbor. This configuration is useful
if you want all ENUM dialing from your enterprise to be configured on one particular system.
ENUM Dialing for Outgoing Calls
For a local endpoint to be able to dial another endpoint using ENUM via your Expressway, the following conditions
must be met:
must be met:
■
There must be a NAPTR record available in DNS that maps the called endpoint’s E.164 number to its URI. It is
the responsibility of the administrator of the enterprise to which the called endpoint belongs to provide this
record, and they will only make it available if they want the endpoints in their enterprise to be contactable via
ENUM dialing.
the responsibility of the administrator of the enterprise to which the called endpoint belongs to provide this
record, and they will only make it available if they want the endpoints in their enterprise to be contactable via
ENUM dialing.
■
on your local Expressway. This ENUM zone must have a DNS Suffix that is
the same as the domain where the NAPTR record for the called endpoint is held.
■
that it can query for the
NAPTR record (and if necessary any resulting URI).
After the ENUM process has returned one or more URIs, a new search will begin for each of these URIs in accordance
with the URI dialing process. You also need to configure a DNS zone if they are to be located using a DNS lookup.
with the URI dialing process. You also need to configure a DNS zone if they are to be located using a DNS lookup.
Calling process
The process below is followed when searching for an ENUM (E.164) number:
1.
.
2.
configured with a Mode of either:
—
Any alias, or
—
Alias pattern match with a pattern that matches the E.164 number
3.
The target zones associated with any matching search rules are queried in rule priority order.
—
If a target zone is a neighbor zone, the neighbor is queried for the E.164 number. If the neighbor supports
ENUM dialing, it may route the call itself.
ENUM dialing, it may route the call itself.
—
If a target zone is an ENUM zone, the Expressway attempts to locate the endpoint through ENUM. As and
when each ENUM zone configured on the Expressway is queried, the E.164 number is transformed into an
ENUM domain as follows:
when each ENUM zone configured on the Expressway is queried, the E.164 number is transformed into an
ENUM domain as follows:
1.
The digits are reversed and separated by a dot.
2.
The DNS suffix configured for that ENUM zone is appended.
4.
DNS is then queried for the resulting ENUM domain.
5.
If the DNS server finds at that ENUM domain a NAPTR record that matches the transformed E.164 number (that
is, after it has been reversed and separated by a dot), it returns the associated URI to the Expressway.
is, after it has been reversed and separated by a dot), it returns the associated URI to the Expressway.
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Cisco Expressway Administrator Guide
Dial Plan and Call Processing