Cisco Cisco Expressway Maintenance Manual
section for instructions on how to do this.
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.
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.
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:
conditions must be met:
n
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.
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.
n
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.
n
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.
accordance 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:
are configured with a Mode of either:
l
Any alias, or
l
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.
l
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.
supports ENUM dialing, it may route the call itself.
l
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:
and when each ENUM zone configured on the Expressway is queried, the E.164 number is transformed
into an ENUM domain as follows:
i. The digits are reversed and separated by a dot.
ii. 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.
Expressway.
6. The Expressway then initiates a new search for that URI (maintaining the existing hop count). The
Expressway starts at the beginning of the search process (applying any pre-search transforms, then
Cisco Expressway Administrator Guide (X8.5)
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Dial plan and call processing
About ENUM dialing