Gateway Configuration
243
(prefered or exclusive) are without effect.
interface with no codec specified.
2. If no interface is present with no codec
specified the call is rejected.
Table
Codec Selection in H.323
Similarly for an H.323 connection it is possible to specify the packet size of the transmitted voice
packets, and additionally announce length capability for received voice packets to the remote VoIP
device.
A
regular
call setup with H.323 requires about 10 TCP segments or more to be transmitted, because
several parameters are negotiated, for example the codec. Because a normal call setup is often too
slow, a fast connect is possible.
Procedure
To configure the used codec on an H.323 connection and enable fast connect
Mode
Gateway H.323
Command
Purpose
25-1:
Step 1
node
(gw-h323)[h323]#codec
<?>
List all available codecs on the H.323 gateway
Step 2
node
(gw-h323)[h323]#codec
codec
[tx-packet-length] [rx-packet-length]
Specify the default codec, transmitted packet
size and length capability for received packets
for all calls over the H.323 gateway.
Step 3
Repeat step 2 to define all possible codecs used
on this H.323 gateway
Step 4
node
(gw-h323)[h323]#faststart
Enable fast connect for a H.323 call set-up
Step 5
node
(gw-h323)[h323]#exit
Change to interface configuration mode to select
one of the listed codecs in the H.323 gateway for
the H.323 interface
Step 6
node
(cfg)#context cs
Step 7
node
(ctx-cs)[switch]#interface h323
if-name
Step 8
node
(if-h323)[
if-name
]#codec
codec
[exclusive]
Define the prefered codec on a fast connect call
set up. It is not possible to redefine the packet
lengths. If the codec is specified as exclusive,
only this codec can be used for the connection
Example: Selecting an H.323 CODEC
The following example shows how to define a list of codecs in the H.323 gateway with 20 ms for the
length of transmitted RTP packets and 40 ms for the announced length capability for received RTP
packets. Further use of codec G.711 on the H.323 interface is specified. Moreover fast connect is
enabled for the H.323 call set up's.
SN>
enable
SN#
configure
Software Configuration Guide, Revision 1.03
Summary of Contents for SmartWare R2.00
Page 2: ......