Cisco Cisco Expressway 维护手册
Each of these address formats may require some configuration of the Expressway in order for them to be supported.
These configuration requirements are described below.
These configuration requirements are described below.
Dialing by IP Address
Dialing by IP address is necessary when the destination endpoint is not registered with any system. See the
Dialing by H.323 ID or E.164 Alias
No special configuration is required to place a call using an H.323 ID or E.164 alias.
, applying any transforms and then searching the Local Zone
and external zones for the alias, according to the search rules.
Note that SIP endpoints always register using an AOR in the form of a URI. You are recommended to ensure that
H.323 endpoints also register with an H.323 ID in the form of a URI to facilitate interworking.
H.323 endpoints also register with an H.323 ID in the form of a URI to facilitate interworking.
Dialing by H.323 or SIP URI
When a user places a call using URI dialing, they will typically dial
name@example.com
.
If the destination endpoint is locally registered or registered to a neighbor system, no special configuration is required
for the call to be placed. The Expressway follows the usual
for the call to be placed. The Expressway follows the usual
, applying any transforms and then
searching the Local Zone and external zones for the alias, according to the search rules.
If the destination endpoint is not locally registered, URI dialing may make use of DNS to locate the destination
endpoint. To support URI dialing via DNS, you must configure the Expressway with at least one DNS server and at
least one DNS zone.
endpoint. To support URI dialing via DNS, you must configure the Expressway with at least one DNS server and at
least one DNS zone.
Full instructions on how to configure the Expressway to support URI dialing via DNS (both outbound and inbound) are
given in the
given in the
section.
Dialing by ENUM
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. The E.164 number is converted into a URI by the DNS
system, and the rules for URI dialing are then followed to place the call.
that endpoint has registered using a different format of alias. The E.164 number is converted into a URI by the DNS
system, and the rules for URI dialing are then followed to place the call.
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.
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.
If the destination endpoint is registered, it may be possible to call it using its IP address but the call may not succeed
if the endpoint is on a private network or behind a firewall. For this reason you are recommended to place calls to
registered endpoints via other address formats, such as its AOR or H.323 ID. Similarly, callers outside of your network
should not try to contact endpoints within your network using their IP addresses.
if the endpoint is on a private network or behind a firewall. For this reason you are recommended to place calls to
registered endpoints via other address formats, such as its AOR or H.323 ID. Similarly, callers outside of your network
should not try to contact endpoints within your network using their IP addresses.
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
188
Cisco Expressway Administrator Guide
Dial Plan and Call Processing