Cisco Cisco IOS Software Release 12.4(4)T

This problem looks very similar to CSCsi27767 which was opened and resolved against the cat6k’s 
Communications Media Module (CMM). But the fix for CSCsi27767 was only intended for the 
CMM platform.

Workarounds: 

User-Level Workaround: A hold/resume from the phone receiving the out-of-sequence RTP audio 
packets will restore normal reception of audio.

System-Level Workarounds: 

1. If possible, use a CMM module for transcoding while ensuring that IOS version on the CMM 
module has the fix for CSCsi27767.

2. If possible, eliminate the need for a trancoder in the audio path for affected call flows.

3. This problem does not affect Cisco IOS Software Media Termination Points (MTPs) nor SW 
MTPs hosted on a Cisco Unified Communications Manager (CUCM) server. So, if like-to-like 
capabilities (for example, codec and packetization) are being used, then using a SW MTP via 
Cisco IOS or CUCM may be an option.