Hi Joe,
Here is the related info for CCM 4.2.3;
Creating Custom Phone Rings
The Cisco Unified IP Phone ships with two default ring types that are implemented in hardware: Chirp1 and Chirp2. Cisco Unified CallManager also provides a default set of additional phone ring sounds that are implemented in software as pulse code modulation (PCM) files. The PCM files, along with an XML file (named RingList.xml) that describes the ring list options that are available at your site, exist in the TFTP directory on each Cisco Unified CallManager server.
The RingList.xml file defines an XML object that contains a list of phone ring types. This file can include up to 50 ring types. Each ring type contains a pointer to the PCM file that is used for that ring type and the text that will appear on the Ring Type menu on a Cisco Unified IP Phone for that ring. The C:\ Program Files\ Cisco\TFTPPath directory of the Cisco TFTP server for each Cisco Unified CallManager contains this file.
Step 1 Create a PCM file for each custom ring (one ring per file). Ensure the PCM files comply with the format guidelines that are listed in the "PCM File Requirements for Custom Ring Types" section.
Step 2 Place the new PCM files that you created in the C:\Program Files\Cisco\ TFTPPath directory on the Cisco TFTP server for each Cisco Unified CallManager in your cluster.
Step 3 Use an text editor to edit the RingList.xml file. See the "RingList.xml File Format Requirements" section for information about how to format this file and for a sample RingList.xml file.
Step 4 Save your modifications and close the RingList.xml file.
Step 5 To cache the new RingList.xml file, stop and start the TFTP service by using Cisco Unified CallManager Serviceability or disable and re-enable the "Enable Caching of Constant and Bin Files at Startup" TFTP service parameter (located in the Advanced Service Parameters).
From this CCM 4.2 doc;
http://www.cisco.com/en/US/products/hw/phones/ps379/products_administration_guide_chapter09186a0080724691.html#wp1030668
Hope this helps!
Rob
