Cisco Cisco Unified Customer Voice Portal 10.5(1)

One-way voice after agent 
transfer

Possible Cause 1:
There is no IP Connectivity between the phone and the gateway.

Possible Cause 2: 
This is a problem someplace in the H323 protocol in Call Manager, IOS, 
or CVP.

Enable IP Routing

Make sure your router has IP routing enabled, in other words, does 
not have the global configuration command no ip routing.

To enable IP routing, simply type the following global configuration 
command in your Cisco IOS gateway:

         voice-ios-gwy(config)#ip routing

Cut-through Two Way Audio Early

In some cases it is necessary to establish a two-way audio path as 
soon as the RTP channel is opened. In other words, before the 
connect message is received. To achieve this, use the voice rtp 
send-recv global configuration command

        voice-ios-gwy(config)#voice rtp send-recv

Check Basic IP Routing

Basic IP reachability should always be checked first. As RTP 
streams are connectionless (transported over UDP), traffic may 
travel successfully in one direction, but get lost in the opposite 
direction. See the above URL for more details.

Disable voice-fastpath 

The Cisco IOS command voice-fastpath enable is a hidden global 
configuration command for the AS5350 and AS5400, which is 
enabled by default. To disable it, use:

voice-ios-gwy(config)#no voice-fastpath enable

Possible Solution 2:
If all the suggestions from Possible Solution 1 fail to fix the problem, 
then this usually turns out to be a problem someplace in the H323 
protocol. Use the logs to try to isolate the problem.

No ring tone heard when 
transfer to IPCC agent

Call Manager has an incorrectly configured service parameter.

In CCMAdmin->Service->ServiceParameters->CiscoCallManager, 
check the value of H323 parameter “Send H225 User Info Message”. It 
must be set to “User Info for Ring Back Tone”.