Hi Rey,
Here is a way of preventing specific users from changing the Ring Volume. This is the only way to prevent users from turning Up/Down this setting;
Users are unable to change the Ring Volume/ and Ring Type if you disable the Settings Access parameter on the Phone configuration page. Complete these steps:
From the Cisco CallManager Administration page, choose Device > Phone, and click the phone for which you want to prevent a ring type change.
Choose Disabled for the Settings Access parameter under the Product Specific Configuration section.
When Settings Access is enabled, you can change the phone network configuration, ring type, and volume on the phone. When you disable Settings Access, the Settings button is completely disabled and no options appear when you press the button. Also, you cannot adjust the **ringer volume or save any volume settings. The option Restricted is available in Cisco CallManager version 4.1(3) and later. When you change Settings Access to Restricted, you can only access User Preferences and volume settings. By default, Settings Access is enabled.
From this doc;
http://www.cisco.com/en/US/products/hw/phones/ps379/products_qanda_item09186a00800a6763.shtml
Hope this helps!
Rob
