Cisco Catalyst 4224 Release Notes page 7

MTP Not Used on Cisco CallManager Unless Transcoding is Required
All H.323 gateways that use IOS 12.0(7) or later support H.323 Version 2. Prior to H.323 Version 2, MTP
was required for H.323 gateways. Ordinarily, the MTP box on Cisco CallManager should not be checked
when defining the Catalyst 4224 as an H.323 gateway. You should check the MTP box on
Cisco CallManager only if transcoding is required at the central site. For example, transcoding would be
required when the Catalyst 4224 uses G.729 for IP WAN calls and the voice mail system at central site
only supports G.711.
With the MTP box checked on Cisco CallManager for the H.323 gateway definition for Catalyst 4224,
a locally connected analog FXS phone call to a local IP phone must traverse the IP WAN because the
call between the analog FXS phone and the IP phone is anchored by the transcoding device at the central
site. This behavior is normal for an IOS H.323 gateway when the MTP box on Cisco CallManager is
checked, but this behavior is obviously not optimal. Therefore, unless transcoding is required, the MTP
box should not be checked on the H.323 gateway definition for Catalyst 4224.
Connecting the Catalyst 4224 as a Gateway Over a Low Speed Serial Link
Use the h323-gateway voip bind srcaddr command to connect the Catalyst 4224 as a gateway over a
low speed serial link.
To configure the Catalyst 4224 as an H.323 gateway, use the following configuration:
This configuration provides the IP address for the H.323 end point. Use the same address in
Cisco CallManager to configure the H.323 gateway. This address can be attached to a physical interface.
Portfast Command Not Supported for Trunks
If the Catalyst 422410/100 Ethernet ports are configured in trunk mode, the portfast command is not
supported. The workaround is to use the global configuration commands for each VLAN to reduce the
forwarding timers to a minimum value of 4 seconds.
Warning If you connect the Catalyst 4224 to another switch, ensure that the timers are the same
on both links. Otherwise, you might experience spanning tree issues.
OL-1798-01
interface Loopback1
description h323 gateway address
ip address 10.253.1.1 255.255.255.0
h323-gateway voip bind srcaddr 10.253.1.1
spanning-tree portfast bpduguard
spanning-tree vlan 60 forward-time 4
spanning-tree vlan 160 forward-time 4
MTP Not Used on Cisco CallManager Unless Transcoding is Required
Important Notes
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