TD 92326GB
2009-03-10 / Ver. E
Installation and Operation Manual
VoIP Gateway
171
with an E.164 Address that matches the called number. If such an entry is found and the
corresponding device is currently registered with the gatekeeper, the call is switched there.
Otherwise the search for suitable aliases is resumed. If there are no suitable entries or the
client is not registered at the time of the call, the call will fail and an alternative route, if
available, will be used (refer to section
Due to this procedure, the called number of a call being switched will be checked twice.
The first time when searching for a route appropriate for the call, and the second time
when searching for an appropriate alias within the “VoIP Interfaces” definition. It is
therefore possible, and normal, to configure routes of this kind very simply using empty
“Map” entries. This means that at first there will be an attempt to switch all calls to the
devices registered by means of RAS. However this will fail, silently, if no device is registered
with the correct number.
As opposed to VoIP terminals, which are registered with the gatekeeper with name and
number, no number is usually entered for VoIP gateways. This would also not make sense,
since the gateways implement an entire number range and not an individual number.
With that, determining the call destination using the called number, as described further
above, won't work.
The gateway specification “GWxx” is insufficient to identify the destination of a call, if
gateways have been registered in a “VoIP Interfaces” definition and a route is supposed to
switch a call there. It is thus necessary here to also enter the correct H.323 name in the
“Map” as “Called name out”.
D.3
Calls to gatekeeper clients via H.323 name
Dialling call numbers is only one way of addressing destinations within the VoIP
environment. Another convenient way is to specify a name as the call destination.
If a call arrives at the gatekeeper with an H.323 name but without an E.164 address (i.e.
without a phone number), the number belonging to the ID is determined first by searching
through all of the “VoIP Interfaces” definitions of the type “gatekeeper client group” for
an alias entry with the corresponding H.323 name. The E.164 address of the first
matching entry is then used to further switch the call in the same way as if the call had
arrived right from the start with this number as the called number.
D.4
Mapping call numbers onto H.323 names
You can map telephone numbers to H.323 names. In this way you can make calls based
on names using terminals unable to call H.323 names (e.g. ISDN telephones).
To do this, enter the H.323 names as “Name out” for the normal routes, see
This procedure only makes sense if the VoIP terminal is not registered directly at your
gateway as gatekeeper, since otherwise the normal methods would of course be
adequate.
